I'm sure there are 29 other reasons to not play for the 29 other GMs in the league, a high majority of them much much worse than Ainge.
I'd go with this. So you sign in LAL, where they traded away Odom (twice), Bynum, tried to trade away Gasol, let Ariza walk after he helped them win a championship.
Or do you sign with Miami who waived Mike Miller after he took a discount to come play there in the first place? Or ships out cornerstone guys like Shaq or Tim Hardaway, or veterans like Antoine Walker to one of the worst teams in the league. Hey they traded for Shawn Marion at one trade deadline, then traded him away at the next. At least the C's let Jeff Green stick around for 2 full seasons (plus the season he sat out).
So you play for Morey and the Rockets? Didn't he refer to players as nothing but mercenaries (although when I google it, I'm not finding anything)? Gave a current player's number away (Lin) to try to lure a free agent. Criticizes the contract Parsons signed (referring to how he wouldn't be able to trade Parsons, why sign a player to a contract you'll just try to trade later?).
Or you play for the Bulls, whose owner openly criticized the Celtics for being too loyal to their players in the past?
Or do you sign with the Mavericks, who had their own big 3, but let a prime Steve Nash walk because they didn't think he would be worth the money, then cut the team's longest tenured player in Michael Finley? The team who didn't give Tyson Chandler the contract he wanted after helping them to a championship, so they let him walk only to trade for him back after a few seasons while still on the same contract they didn't want to offer him in the first place? Actually, hasn't that whole team just been considered Dirk and a bunch of mercenaries for the last several years now (this season for instance, besides Dirk, they didn't have a single player who had been on the team 2 seasons prior).
I'm sure if I actually followed these teams (or any of the other teams in the league) I could come up with many more examples.