If it´s true what @RonGilbert says and her character´s role is loosly based on the movie Re-Animator she is really lucky in comparison!
Then show us
Every other version I have tried locked the gate and you cannot switch character e.g. to open from the other side.

Yep. I’ve just played that section again and can confirm the following: if I keep moving during Dr Fred’s dialogue and go straight through and put on the hazmat suit, go through the door, turn off the switch and pick up the meteor without stopping to hear him out, the timer never starts!
Yes that’s fine. Fred is the one who initiates the self destruction under influence of the meteor. If you break the influence before he can do this it makes sense to have no timer.
Maybe this was improved/fixed in v2?

Then show us
Every other version I have tried locked the gate and you cannot switch character e.g. to open from the other side.
I´m pretty sure it works for deluxe at least(they removed a few other dead ends there, too). But I can´t capture anything on my pc, so…

I´m pretty sure it works for deluxe
Oh OK, this may be possible.
But I think we are mainly talking about the official versions and ports, Deluxe being a fangame doesn’t really count
That´s true, also the NES port was done from scratch and it´s possible that this may have been an aspect the makers of deluxe took into their version because, again they removed a few dead ends and added stuff like the packages appearing next to the tombstones (which also can remove dead ends).

Yes that’s fine. Fred is the one who initiates the self destruction under influence of the meteor. If you break the influence before he can do this it makes sense to have no timer.
That would make sense, except that if I intercept him Dr Fred still says afterwards that he needs to turn off the self-destruct mechanism (even though he didn’t set it in the first place). But maybe that’s more a dialogue bug.
Usually he should initate the timer as soon as you enter the lab.
From: http://www.maniacmansionfan.50webs.com/
You’ve found Dr.Fred and Sandy! Dr.Fred will call Purple Tentacle to the rescue, to no avail. He will then start the house’s self-destruct mechanism and you’ll have two minutes to beat the game before the house explodes.
Walk to the right and open the locker. Pick up the radiation suit. You’ll need it to protect yourself from the Meteor’s radiation waves. Use the card key inside the card slot to open the door. Go through it. Turn off the switch. Dr.Fred then comes back to his senses and attempts to turn off the self-destruct mechanism, but the Meteor prevents him to.

Fred is the one who initiates the self destruction under influence of the meteor. If you break the influence before he can do this it makes sense to have no timer.
In that case there would be enough time to feed the meteor to the plant even in the C64 version.

Yes! Please do so I can feel like the omniscient one this time
I fear that I remember the most puzzles. I have even my map that I’ve drawn for Space Quest 1.
But maybe you have an adventure game on your list that we (all) haven’t played? So we can solve it together? (Forming the ultimate Thimbleweed Solver…).

Usually he should initate the timer as soon as you enter the lab.
Yes, that’s what I remember: At least in the C64 version there wasn’t enough time to walk over to the lever and switch the brain control off. But you can stop the timer under certain conditions - but I can’t remember which ones…

But you can stop the timer under certain conditions
Sounds like an exploit or glitch. The whole point of that finale scene is that as long as the meteor isn´t taken care of even reasonable Dr. Fred can´t stop the countdown. Unless the meteor already has been removed by the police in Bernard´s ending.

even in the C64 version.
As long as the gate opens, that is…

But maybe you have an adventure game on your list that we (all) haven’t played? So we can solve it together? (Forming the ultimate Thimbleweed Solver…).
Sounds like one cool idea!

anyone fancy playing Space Quest?!
Yeah, I just started playing the series. Although I did play a bit of SQ4 when it was released, but put it down for being brutally hard.
I’m also in the middle of KQ, and I’m in dubio whether I should play them per series or more chronologically (to appreciate cross-game jokes). In the latter case, I should also include the Larry games.

In that case there would be enough time …
I’ve watched several let’s plays: On the C64 version there isn’t enough time to reach the switch. So Dr. Fred sets the alarms every time. In the Amiga version there seems to be enough time - but I haven’t tested it.

The whole point of that finale scene is that as long as the meteor isn´t taken care of even reasonable Dr. Fred can´t stop the countdown.
Yep, you are right.

But maybe you have an adventure game on your list that we (all) haven’t played?
One that I haven’t played as well, or that I can help you through? Either way sounds fun!

Although I did play a bit of SQ4 when it was released, but put it down for being brutally hard.
I did the same with SQ2, which was the first one I played. I only completed it (and the others up to SQ5) as an adult! Let me know if you need any hints. There are some bloody ruthless dead-ends in that series.
Going back to Dr Fred and the meteor - there’s only jus enough time to intercept it - it’s pretty tight! Shame it’s not possible to do the Audrey 2 ending given the freedom of time - or maybe it’s only certain characters?

One that I haven’t played as well …
This!

Going back to Dr Fred and the meteor - there’s only jus enough time to intercept it - it’s pretty tight!
On the C64 version Dr. Fred begins to enter the numbers when you open the door. It would surprise me if you can reach the lever in time (on the C64 version).

On the C64 version Dr. Fred begins to enter the numbers when you open the door. It would surprise me if you can reach the lever in time (on the C64 version).
This is even played out in cutscene mode. You can´t move when the door closes behind you and until he finished his dialogue. There is just no possible way.

Shame it’s not possible to do the Audrey 2 ending given the freedom of time - or maybe it’s only certain characters?
It’s possible with the NES version and the fangame Maniac Mansion Deluxe seems to have adapted this ending.
But I’m pretty sure it’s not possible with those other versions, I have tried it in the past!

This is even played out in cutscene mode.
No, you can walk, grab the suit and open the door while Dr. Fred is talking. But the kid is too slow to walk to the other room before Dr. Fred enters the code.

But I’m pretty sure it’s not possible with those other versions, I have tried it in the past!
If I remember correctly you can’t feed the grown-up plant anymore. So it looks like it’s a feature of these versions…

On the C64 version Dr. Fred begins to enter the numbers when you open the door. It would surprise me if you can reach the lever in time (on the C64 version).
Yeah I doubt it’s possible in that version – I just meant it’s even only just doable in this one.

you can’t feed the grown-up plant anymore
I wouldn’t know because I cannot get there. The gate is always closed (‘It’s locked’) and the other way out too (‘It’s sealed shut!’).

No, you can walk, grab the suit and open the door while Dr. Fred is talking. But the kid is too slow to walk to the other room before Dr. Fred enters the code.
This is true, you can walk. But it’s not a problem with the DOS version (v1) in ScummVM to do this.
I don’t think it’s a bug that you can move (e.g. it should be a cutscene; but this would have been probably fixed in ScummVM a long time ago).
It just may be that with ScummVM plus a proper mouse and no loading times you can make it (I just tried it with v1, as @PiecesOfKate described).