If he isn't trying to move and the bloodbender isn't trying to move him, it's impossible to even tell there's anything wrong. Except for all the things that are really obviously wrong. It's impossible to tell there's bloodbending going on, anyway. So it's a few minutes before he tries to move his mouth and discovers that he's allowed.

Okay. Crap. What does he say.

"...Want some more animal trivia?"

Great. Yes. Awkwardly semi-flirt with the bloodbender. That'll help.