That's completely different though. Banning the conversion of btc into real currency would be a huge problem for btc, who is going to accept btc in exchange for a product or service performed if they can't turn that btc into money to exchange with other individuals/companies? There needs to be a much wider acceptance of bitcoins by companies providing services/products over a longer period of time before banning the conversion(at least legitimate conversion) would no longer phase bitcoin.