I...I don't get it. There's no reason to betray MC here.
The traitors initial concern was that MC might be evil and planning to enslave or harvest their organs since he saved them for no reason and brought them to this heavily fortified isolated shelter in the middle of nowhere—which was a pretty valid reason for not trusting him. But, they've been together for a few days and the MC's been pretty good to them. It's clear he has no nefarious intentions.
Like, what's the traitors endgame here? MC treated them all so well that no one would side with him. Is he really planning to kill them all and take everything for himself? A army of people literally tried raiding this place the 1st few days of the apocalypse, there is no way he can hold that entire place on his own. The traitor claims that they're basically slaves to the MC right now, but they're the most well fed, well armed, and well protected slaves I've ever seen in an apocalypse.
Dumbest betrayal I've seen in awhile.