I don't think anyone is questioning that, only if freezing people is remotely standard procedure. I agree that most everyone acts as though it's risky only due to Cloud City's facilities, but the one line that is hard to make fit is Lando's, "Lord Vader, we only use this facility for carbon freezing." Well no shit, Space Sherlock. That's what we're here for. Unless he means that they use it to freeze carbon, as opposed to using it to freeze other things in carbonite.