Such an important change to the fundamental question, is a president subject to law, has to be 9-0 or it should not be done at all.
The old rule, that there is a thing called the rule of law, to which everyone is subject, was simple. It hardly needed to be invoked because presidents take legal advice. And no court would entertain a challenge to a president's use of his core powers.
The new one, with its absurd undefined grey area, (not even a test being defined) makes trying a president for, say, inciting a coup, pretty damned difficult. Any future president will ALWAYS cloak his criminal intentions in an official disguise.
This feels a bit like a nail in the coffin of American democracy. It's the end of your relationship with English law in which EVEN A KING is subject to the rule of law. We executed a king who thought otherwise. SCOTUS has found a way to make that almost impossible in any practical sense where a president is concerned.