
Teach is kinda forgetting they're living in an apocalyptic world

Yes, that could be true ideally but it's more complex in their setting. Post-apocalyptic world, resources are scarce, and their place is probably the rarest safe zones. Those people knew what Guwon (or his mentality) is and still stayed and agreed to the rules to be protected. If exceptions are made, no matter how emotional, then rules are no longer rules, but guidelines subject to whim. Fear of punishment is sometimes the only thing keeping desperate people from acting selfishly. If people see that well-intentioned theft can get away with it, people will follow and there's nothing left to save. Carrying out the punishment is a way to show no one is above the law, Guwon follows those rules himself. It's also kinda selfish/cowardice of Teach to only criticize Guwon when he saw all the others vote as well.
Got me giggling, toe-curling, and shit