Wait a minute-fans would needle Roddenberry about elements of the licensed material in person? Wow. Did you ever get to see this? How did Roddenberry react?
How does any guest react at a convention?
Answer: it varies.
Every convention experience is different, and every guest could be having a good or bad day, but inevitably at any Star Trek convention, people will tend to ask certain annoying/stupid questions over and over again. This can either make the guest laugh it off, or get a bit testy, depending on any number of factors.
I never saw GR at a convention, but I've heard plenty of tales - and sure, every now and then someone would ask him something a bit ridiculous, such as why Kirk didn't take a particular action in one of the movies, using tech which had only ever appeared in a Star Trek licensed tie-in book. Or why the movies ignored Konom, the Klingon turncoat from the comics. Or why Caithlin Dar in ST V wasn't called a Rihannsu. Etc.
Sometimes GR laughed. Sometimes he sighed. Sometimes he tried to explain patiently that licensed tie-ins, even though Paramount approved, shouldn't be informing the series. And sometimes he got angry back in the office and wrote a few reprimanding memos.
Richard Arnold began explaining to fans about "canon", so that people might understand why not to ask dumb questions, I guess, and away went the whole mess from there. And it didn't stop dumb questions being asked.
The only time I recall a story where GR was getting very testy while on stage was replying to the "Bring Back Bev" campaigners at a convention that "if he listened to the fans then Star Trek would be shit!"