He could have said "Well Arnold, I'm a genetic freak and to be honest I don't have to work too hard for my condition - unlike some of the guys onstage today" and people would have thought a lot better of the guy.
His lack of ability to be forthcoming makes people think he's a tosser. Which he probably isn't.
Kudos to Arnold for doing a good interview. A guy like Dexter is just about your worst interview candidate.