It's not black and white, though. They literally need to work with them or they all die, because they tried everything else and failed. On top of that, they made rules specifically to keep these villains at least somewhat well-behaved, and have punishments for those who don't. Troublemakers are the exceptions to the rule, and people will fight to stop them. And for the villains they brought aboard, most of them have stopped terrorizing humanity. Some genuinely became good people. Taking them in has probably made the world safer.
There's X-Men Green, but... That's X-Men Green. I'm not sure even the writers know what the heck is going on with that train wreck.