Yeah, in all honesty I don't fault Cyclops decision to form X-Force. When the uber-Sentinel wiped out Genosha it was horrible, but there were still a ton of mutants (and more being born virtually every day). Now there's a pathetically insignificant number (in the grand scheme of things) and as noted, some of these extreme hate groups have a very real chance of wiping out mutantkind seemingly forever.
Cyclops and the X-Men can't afford to wait around for one of these groups to pick off one or two or a dozen of the remaining mutants just so they can be "justified" to fight back.
Now...putting all your people on an island in San Francisco Bay? I'm having a hard time figuring out the tactical and strategic soundness of that plan. You may as well artfully arrange the buildings and hedgerows into a giant bullseye.
That or hope to god that one of these higher-tech hate groups don't come up with a stealth-bomb. Or that Norman Osborn doesn't convince the public that you're a genuine threat to national security. Or any number of scenarios where it's a whole lot easier to kill the remaining mutant population when they're all holed up in one place.