If I was him I'd get pretty pissed off. "Ha ha, great! Thanks for knowing one thing about me! It is great that you're aware of what I used to do for a living! Very amusing! I wish I was 20 years younger and not shaking to death from a horribly degenerative disease, because then I would pretend I didn't know you were joking and cave your fucking skull in with a left hook."
Plus, does anyone do this for any other profession? You don't see people faking left and going in for a layup when they meet Bill Bradley, or pretending to type at an imaginary keyboard when they present Susan Sontag with an award, or, I dunno, acting like they're throwing it to some emaciated blonde when Ron Jeremy comes by to drop off a check to their charity.