I don't know if Pizza man left of his own accord or not, doesn't really matter, but I do feel he was held back in what he could say or respond to because of the nature of some of the decisions made by WGT in how to serve the community of players. Some of their decisions clearly indicate that WGT's intentions are 100% profit based, and they are entitled to making a profit, that is how they manage to stay in business. I do think that Pizza did try his best to respond to issues but was limited to what he could do or say and that frustrated him. He didn't always say what he wanted to say and did come across as a bit arrogant on some things but that may have been driven by his limitations.
Pizza and Icon both have a tough job. The difference in the two moderators is clearly evident. Icon will say what he has to say and leave it at that, you rarely see him engage more than once on a subject. Pizza however would try to make his point, then come back to defend it time and time again. That is probably what frustrated him and led to his leaving. Cest La Vie. Icon, on the other hand, was respected because of his playing ability as Iconian, and people look at his stats and know that he at least knows what he is talking about.