Separation of powers and remedy can be tricky. Whose job is it to check that the president "Take Care" and enforce Congressional Act. I think it is Congress, which is the most dysfunctional and worthless institution on the planet. If Congress thinks the president has violated his oath, impeach and remove him.
That gets the heat out of the court system, which is job number one.
Merits? Ha!
Based on THAT presumption, O’Care should never have been allowed, as Congress has NO/NONE/ZERO/NADA A1S8 authority to tax for!
Even still, the Court could essentially say, “It’s illegal, but up to Congress to rectify”, which would put Zero on notice and give the People their reasoning. If Congress refuses to do their job (again), the People have the means to fix.