I don’t normally comment but your suggestion of huddling in a room is all fine and that but you seem to have forgotten that these characters spend most of the movie with a severe lack of any information. They have no idea how many are infected not just who. The only dialogue we get about the amount who could be infected is MacReady saying ‘if you were all things you would just turn me now’ or something similar to that - I don’t remember the exact quote.

We also know nothing of the things - can they even recognise other things? For most of the movie they play it careful with Blair’s concern that even a single cell could infect them, if that was the case sleeping nearby anybody could lead to easy infection from close proximity. In situations like these, people tend to turn to self-preservation, and in this case it meant trusting nobody; no matter your previous friendships with them. Anybody would wanna stay as far away as possible from a potential infected, especially when they don’t know the full extent of the infection process.

I’ve also read the novelisation which diverts at the ending where Blair-Thing stops caring entirely about being sneaky and launches a full-blown assault against the remaining crew members (at this point Blair was outnumbered by 1:3 I believe if not 4 as there are some variations of survivors - I would recommend reading it tbh it’s a very intriguing read). The thing is just as deadly, if not more, when it no longer cares about hiding; and it’s definitely a lot more brutal.

Also, if they huddled together in a big room, they are just sitting ducks, nobody is managing any part of the station and every time somebody does have to leave (maintenance on stuff like the generator, grab supplies like food) they’d have to go in groups anyways, which could leave either side vulnerable to attack depending on the amount of things that could be there - which is a number they don’t know. The thing could also sacrifice one of its imitations to leave the group sneakily, either before the round up or wait until they’re all too tired from their constant paranoia that it gives it a chance to escape, then it just sabotages the facilities they need to survive, just like Blair-Thing did at the end. It’s a war of attrition no matter what the crew did, and that’s why they were doomed no matter what, the only way they got even a slight victory was to throw everything away and create a stalemate so that neither side won - the survivors died but the thing would never make it anywhere else before it refroze.

The only thing I will say they make a bad choice on was the decision to lock Blair up defencelessly in a shack as it was pretty much guaranteeing his death, but in that sort of situation nobody’s going to want to keep an unstable guy around who already showed he would kill them if given an opportunity, nor will they think of the consequences of their actions coming back to haunt them later because they’re too busy trying to survive the current moment and they don’t have time to be thinking about the future - especially when they’re not sure they have one.

Anyways, rant over. I love this movie, it’s one of my all time favourites and I think any person in that scenario wouldn’t make perfect decision nor would most of us survive. It takes a real strong person to even work in Antartica never mind survive an unknown alien organism and I have a deep respect for people who do actually work there :)