I don't see how Lucas could have reasonably reserved such a right. Disney owns the Star Wars IP and thus can do what it wants with it. The only way Lucas could exercise that control is if he did not give up full ownership. That's a cumbersome prospect which would turn off any buyer.

The problem is what happens if Disney releases the OOT, despite some kind of clause against it. Ownership reverts back to Lucas? Disney has to pay a fine? There is simply no reasonable way to enforce such a clause once Lucas actually sells all his interest. It's simply contrary to the fact that Disney owns Star Wars.

I agree with others on Fox, there's no reason Fox wouldn't want to make a ton of money.