The grunt that follows is amusement and agreement, and even if there's no comment made or discussion offered, Jacobi should know that he's gotten his way. The lack of 'no' is more likely than an affirmative on this kind of thing.

When it seems like the topic's been dropped, in fact-

"Samoa. Not just coconut."

He's never made Jacobi pay for food their entire career together. He knows perfectly well he isn't going to pay for anything. The offer is a feint if an appreciated one.