Don't businesses have free association? Why should I have to allow someone into my business who has sued me?

James Dolan: "If any law firm in New York takes a client who plans to sue me, then all employees and their families of that law firm will be banned from any event at MSG".

Leaving aside the fact that it is the client suing, the law firm just represents them (as generally, or at least for all intents, is required by law)...

... this is no different to a SLAPP. Whereby Dolan knows that very few law firms are going to be willing to represent a client who wants to sue MSG.