It's true that effective salaries are zero sum, but my point was that teams plan to the cap, and contracts are distributed as such, so we shouldn't necessarily expect to see a change in contracted values.
So in that scenario, the net impact of an extra 1-2 million dollars going to a star is trivial when spread out among all the other guys in the league.
It may not make sense to you, but the reality is that the optics of stagnating salaries for top end players is bad for the PA. Optics are critically important for labor unions, and losing support among their most valuable members is the last thing they want.
If the PA were really concerned about high salaries for stars stealing from everyone else, they'd push for a lower max AAV, which I'm sure the league would be thrilled about. Ask yourself why that hasn't happened.
I disagreed with your conclusion that the PA wouldn't want their stars making more money.