Saying something is confirmed by IMDB is like saying something is confirmed by the National Enquirer...
It says he is playing a "Nibirian Elder", which seems pretty specific for it just to be intentional misinformation by an IMdB contributor.
I mean, the actor is a real guy, and that is really his stage name. It wouldn't surprise me if his agent sought out the production, or if the casting director knew of him and thought it would be fun casting.
If the character is a minor one, and the actor can do just as adequate job as anyone else, then why not cast an actor named "Gary-7"?