I think Trump already knew about this guy, that is the reason he ask him if his wife was aloud to speak
Like Ricky Roma said in Glengarry Glen Ross, 'You never open your mouth until you know what the shot is.'
And you can bet, Trump knew what the shot is.
Trump has hired tens of thousands of people from all backgrounds. His Human Resource department has to be one of the best. Of course he has known about this guy since his name first appeared on the list of speakers