Despite what the Hellfire Club intended I don't think freeing all those mutants is going to turn out to be a good thing. Don't get me wrong, I am not saying all the mutants deserved to be there or are bad. But not every mutant is going to be nice or peaceful. Look at Rebecca, she had issues even before she was locked up. And even if the good mutants were locked up who knows what their time in confinement has done to their mentality. So even if they beat the Club I do not doubt more bad guys are going to show up to cause problems.