Any NBA GM is ready to trade any player that isn't Michael freaking Jordan (he got traded to a baseball team) at any time.
It is the GM's job to win.
List a Celtics player who wasn't ever under consideration to be traded by Ainge.
List all of the "home grown" title teams of the last 15 years, I'm sure there are some, but the other GM's have to do their jobs.
If a star shoots his way out of town? That means the star is the "GM" and he's "trading himself".