You guys are forgetting something.... the show is far more "engineered" than it used to be.
Who goes on stage and how the program is cut is strictly up to the personal judgement of various staff members. If your name is Joseph, and you want "Joe" on your nametag, or if your name is William and you want "Anna" on your name tag, so long as that doesn't present an image they don't want to display, they could easily allow that. If you want "Zorbo, Master of Silliness" on your nametag, the easiest thing for them to do is put "Zorbo" on your nametag, seat you in the back, keep you out of any camera close ups, and not call you up on stage, all of which are their legal right to do, and as part of the conditions of attending the taping, things you simply have to accept. If you make a scene, they kick you out, no questions asked, and they could even ban you from ever returning. Now, whether they operate that way or not, I don't know.... but they COULD, with no legal (or moral, for that matter) wrong done in any way, and no one could sue them successfully because they wouldn't be able to prove any harm. The show could easily argue that seating and selection are entirely based on who they think would make a good contestant, and 300 other people weren't called either, and 75 of them were in "bad seats," and that many people have attended multiple takings without being called because selection simply isn't random.