It occurs to him at once--Jesse doesn't know. 76 isn't sure whether he should be relieved or not, but this puts him a position where he can break the news himself, instead of waiting for McCree to find out from Reinhardt, Ana, or worse, Gabriel. Loath as he is to give up the charade, he already knows there isn't a point, and at the very least he can now confess on his own terms.

"You've got no idea, do you?"

There's sudden disbelief in his voice as he drops his hands to his side, all at once a little bit exasperated.

"Reinhardt didn't say anything?"