Yes, this is a reasonable concern, I agree. One could argue that a buyer actually planned the bailout to capitalize on Gox users, who, obviously, are going to pay some percentage of their balances for the whole operation. However, Gox customers don't really have any other choice, so they'd take the deal.
One can suggest that this kind of tactic will never be again used in the future, since all exchanges would be audited and customers would be more cautious.
I can almost guarantee you that if such a bailout happens that it will likely encourage such behavior in the future. Rewarding a behavior encourages that behavior, whether it is good or bad.
In the future all exchanges could be audited and customers more cautious, but if something catastrophic happened then there would be those demanding another bailout because a precedent had already been set. Even those protections mentioned would likely stagnate over time.
One can suggest that this kind of tactic will never be again used in the future, since all exchanges would be audited and customers would be more cautious.