Well he fukked up by entertaining that dumb shyt to begin with. As soon as she said, surprise my whole families here
He should've dipped immediately
He was probably caught off guard but wasn't worried about the financial implications.
His reaction is understandable as situations like that put you on the spot. Imagine if you're going on a date and other people show up. You're in a situation where others are watching you. You can almost get gaslighted into thinking you were wrong for thinking it was a date.
Probably gathered his thoughts throughout the meal and bounced. Decided that on principle he wasn't having it.