No, it isn't a question, so Benjamin doesn't give a response.

He doesn't bother protesting that he has a bill to pay, either - merely leaves leaves enough cash to cover his lunch and a decent tip, and gets up to follow Harding into the building.

"You couldn't leave me behind if you tried."

Not that he believes Harding would. Quite the opposite, in fact, which is one of the reasons why he'd called him in the first place.