J doesn't respond - he can hear the distraction creeping into Bone Man's tune, and he doesn't want to disrupt that with chit-chat. Priorities, after all.

Turns out that's a good decision - distraction leads to recognition, and the tune rolls on, the strongest J's heard it since he got here. Bone Man's back is turned to him, and he makes a split-second decision, quitting the finger tapping and breaking into soft-shoe without missing a beat. It wasn't going to have the same enthusiasm or effect as a full-on mission, but it definitely has more power than finger tapping, and he's going to use it as best he can to keep supporting and fixing up that tune.

And if Bone Man even starts looking like he's going to turn around, he'll find J exactly where he left him, completely still, quietly tapping his fingers. J can turn on casual in the blink of an eye - evidently it's a talent he's gonna need here.