"And I have no reason to trust you." The Jedi here were perfectly able of doing good when it intersected with their own self-interest, but after finding out about the chips? Any slow, shaky trust he'd had in them was gone.

"It's already out." His mind was safe--at least unless Jedi sorcery got involved. Rex, though, with his conditioning--"Don't even try commanding any of us."

Rex was private about a lot of his experiences, and he didn't pry. But the last big anomaly had given him a look at Rex's first deployment on Geonosis, and what a horrifying mess that had been for the troopers, stuck under Jedi command. He didn't want Rex to ever get trapped in that situation again, not as long as he could do something to help.