Freedom of speech in government is worlds different than in private organizations that have conduct/behavior requirements in their contracts.
Yes, but private organizations can dictate what their employees say and do. A television network can dictate what their show hosts say and do. A commercial sponsor can withdraw their funding if they don't like the message that is being sent.
When you are the owner, though, you own something. You have property rights that are just as sacred as the right to the house you own. Donald Sterling owns the property that is the LA Clippers. I have a hard time believing the league can actually take it away from him or force him to sell it to them if he doesn't want to.
And a lifetime ban is very similar. Oh, so I can't make personnel decisions for the team I own, eh Adam Silver? Kindly go F yourself, I own this team, I'll sign whoever I want.
In the end the league will slog him down with litigation and they will come to some sort of agreement that he turns over control, like what happened with Marge Schott, but I'd be shocked if you ever see a Court actually order that they have the unilateral power to deprive him of the right to run the team that he owns.