The best analogy is that being a team owner us like owning a house that’s in a HOA. You don’t get to buy the house without signing the covenants, and then you have to live by them.
I’m guessing that the ownership covenants/agreements have clauses about not bringing disrepute upon the League, with the Commissioner being the arbiter and fellow owners the path for appeal.
Since this was a private conversation between two people engaged in, ostensibly, an intimate relationship I’m certain that Sterling’s going to challenge this in the courts that whatever covenants are being applied really don’t. Assuming he’s allowed to go to the courts, because the covenants may have restrictions on that as well.
But at the very least he can sue and see where that leads him. A much better option, IMHO, is for his family to interrupt the sale decree by having him declared mentally incompetant (the conversations were being recorded, remember, at his own behest due to age related cognitive impairment) and demand that they be given custodianship of his assets. Including the team.
That would really throw a wrinkle into this, now wouldn’t it?
If you are not a lawyer, you should be.