I'm thinking the NBA has a possibly solid case upon reading the two clauses posted. Article 35 deems Sterling racist comments a violation. Article 13 states if a clause is violated willfully, the Board of Governors can terminate said perpetrators membership.
The key is, this a willful violation? Sterling's only defense against his statements would be some type of mental disorder or coercion. I'm waiting for the old fart to pay some phony doctor to make some bogus claim.