There are several other exchanges which can be used nearly as easily as Mt. Gox. Next time you want to send funds to an exchange, don't make the same mistake, ok?
So they are entitled to keep the $100? What would you describe that as? Profit? They certainly provided no service. I agree that any exchange, MtGox or the alternatives, are free to create whatever policies they like, however stealing user money under a pretense is deplorable. If stating that fact sounds like 'whining' to you than I would question your neutrality in the matter.