I'd like to add a more moderate voice to this debate:
I have no problem giving Avery credit for wanting to win, maximizing his talents, and being a vocal leader. I just don't think that is enough to merit jersey retirement. If the Spurs hadn't signed Mario, I think most would agree that it would have been pretty unlikely that they win the '99 le. If Avery hadn't been on that le team, and hadn't hit that one jumper to clinch, would we still be having this debate? I doubt it. Take any other jersey up there and take away one signature moment; they all would still have a jersey hanging in the rafters. Not so with Avery. (Moore and Elliott notwithstanding; recovering from desert fever and a kidney transplant to play for the Spurs again are dramatic enough to transcend the traditional tests for jersey retirement; and even then, lots of fans didn't agree with the decisions.)
As I recall, Mario wasn't run out of town because he was too vocal. He was released because he lost his effectiveness defensively as the rules changed and he couldn't compensate for a lack of quickness with physical play as much as he used to. You don't bring a guy who's too vocal for the team and wears out his welcome back to be an assistant coach - you bring leaders back.
One other thing I'd like to mention - stuff beside on the court performance does matter. At least to San Antonio. The two most recent retirees - David and Sean - are as beloved as they are because they have embraced this community in a way that few other athletes have. They are icons now. As others have said, Sugarland, not San Antonio was home to Avery. For a lot of us that counts. But here's what counts even more:
As much as I respect Avery for what he did as a player, I think he has shown himself to be petty and ungracious at times since he left. The argument the Avery defenders use - that he was already gone, with a different team, not the Spurs leader anymore - neglects one simple truth: Put Pop, David, or Sean in the same positions as Avery - both as a former player and then as an opposing coach - and they would handle themselves with more class and discretion. When have you ever heard Pop make comments like Avery made or lobby for calls shamelessly like Avery did in the press in the '06 series? Never. That is a big part of who the Spurs are and what they Stand For; and for me it is the reason that ultimately makes my decision a lot easier: I don't think Avery's jersey belongs in the rafters.