There is going to be quite the legal battle over that $30M. AB will certainly file a grievance against the Raiders arguing that his behavior wasn't "detrimental conduct" and that the Raiders were not entitled to void his guaranteed money.
IF he were to win (seems unlikely), not only would the Raiders owe Brown that $30M, it would all accelerate and be dead money on this year's cap.
That would mean, in total, AB would be counting for $50M in cap space to 2 teams he never played a down for this year.