I don't know if they have to.
I've heard talk recently on FR that that is exactly why Roberts did what he did, and that he could foresee CA-RATs and other RAT-voters whacking-out about the high premiums and no benefits...can't find a doctor etc.
(Nyuck nyuck nyuck!)
so, Roberts essentially put the Congress in the vise grips of public opinion to redo, reset the failure.
That is what is happening now. There will be a new congress acting on perhaps three rulings. The Presidnt will say.... I tried but the court destroyed all our good work
Win/win = win