While it's pretty obvious from the "Return to Murder House" episode that the Harmon and Langdon ghosts won't be making friendship bracelets with Michael anytime soon, there's something to be said about the allure of freedom. Who knows what the ghosts would do if Michael promised them the sweet release from the house they've been trapped in for eternity? After all, we saw how Moira yearned to be at peace — why wouldn't the others jump at the chance to get that kind of happiness? Helping Michael wouldn't be that big a price to pay since they're all dead anyway. The apocalypse wouldn't have any effect on them.