He doesn't quite believe that. Also what are the stipulations for murdering for fun, here? He's not went spree killin' or nothin', and he's not some serial killer. But the heat of a fight? Or someone he hates a lot? Oh it can get fun.

But considering what Soldat's said about Hydra, he figures that's not what he means.

"I'll hold you to that, 'cause I mean if you did I'd slap it right back outa your mouth." Probably not prudent to threaten people, but the fact is he's threatening 'cause he's terrified of the idea of exposing himself. It's not boisterousness or normal hostility, it's just quaint and timid fear.