To be fair, Trump is far from the first to practice selective enforcement. As long as cannabis remains schedule 1, the DEA could raid every dispensary and farm in states that have "legalized" it, the only thing stopping them is our presidents turning a blind eye. All those "10 ridiculous laws still on the books" listicles operate on the same principle: nobody cares to enforce them, and since nobody is enforcing them, there isn't enough political will to repeal them, either.

Which is to say SCOTUS will absolutely approve of Trump refusing to enforce laws he dislikes, for better and for worse. The emergency declarations to enforce unconstitutional rules he just imagined like an LLM hallucination will likely be far worse, and even if SCOTUS says no, I doubt he will obey them (SCOTUS has no enforcement powers, after all).