Hayden says Amber is following us around and she's with Caleb and Devin but they had nothing to do with anything that might ever have happened at anytime. So there.
Seems to me like Zach needed a reason to expose the bomb squad which is why he told Devin to put him up, because he believes the house will unite against Devin by keeping him.
Actually, I think he has lost some votes by doing so