Corey knew that he had to confront Brayden about what was going on but Brayden went straight to Glenn's tent.
This was a surprise because there was no way that Corey would be able to stop him without things escalating but this would also be the perfect opportunity for him to scout the camp further without suspicion.
He knew that Glenn wasn't stupid, giving away their plan would be him going against the camp, and this was punishable by exile. In other words, throwing away his life for a group of strangers.
He was a raider so he was no stranger to difficult choices and that meant he had done some things he wasn't proud of, they all had.
Glenn might look innocent but there was no one innocent left in this world because killing became something that they all do, be it the living or the dead.