Self-preservation is the top priority here. That, and making a good showing for the folks back home.

So when Sigma signals for him to halt he does, albeit with a look that says he better keep talking. He wouldn't kill him for his gift, no, he's not prone to wasting something useful like that. Of course, this could all be some distraction tactic so the old man could shiv him in the back at the first given opportunity. Who's to say?

Rumlow's jaw works tight in frustration, but he's obviously willing to listen. For now.