My guess would have to be Arroyo walking out. I don't believe he thinks he can beat Danzig. That's only what i think.
Really hope Tommy fights. I've a lot of respect for that dude right now. The kid has so much heart. And i actually think George has to be a little worried about his strength.
I highly doubt Arroyo is going to walk out. If anybody walks out, I think it would be Danzig, because he believes he is on a whole other level, and risking a loss to Arroyo would 'damage' his career. He probably feels like he's earned enough respect on the show and doesn't want to lose. I bet he gets really frustrated or causes a big scene and leaves. I like Danzig, but this is the only scenario I would believe.