At what point did the sniper realize or THINK that Stu was "giving him the silent treatment"?

And even if he thought he was being quiet on purpose, could he not instead have asked him "Hello, can you hear me?" or "Hey, what's the matter, cat got your tongue Stu?" or "You got something to say" etc etc etc.

Yeah, I know he was teasing him afterwards with the whole "my mother used to do this, you're bringing up my childhood" and he was probably too afraid to shout back "Oh shut up!" in anger etc but still...