No, that's not true. It's very possible that some terms are enforceable and valid while other terms are not. Apple takes a risk in trying to enforce the "on Apple hardware only" clause, and I am sure even their own lawyers have cautioned against risking a judgment which states that this clause is not enforceable. I say this as a Mac user and a promoter of Apple products. That doesn't mean I think a company should get carte blanche authority to determine how its products can be used. If you want to fully control something, don't sell it as a product on the market.