If he was referring to the 2024 SCOTUS ruling, I guess I expected him to spell it out well enough for an armchair lawyer like myself, but you are probably right. Though I wonder if the "encroach" wording could be about the Supremacy clause and separation of powers (him being a state judge encroaching on the elected federal executive.) He wrote a lot at https://www.nycourts.gov/LegacyPDFs/press/PDFs/People%20v.%2... but I can't tell how much this SCOTUS ruling weighed into it. There are references to "presidential immunity" that, I think, encompass older cases than the 2024 one.

Anyway, in agreement with your larger point, the legal analyst at https://youtu.be/4tbaDI7ycrA?t=592 says he believe this SCOTUS would not have allowed a real sentence, so my nitpicking about the interaction of the 2024 decision with the lower court's sentencing doesn't matter much; SCOTUS would have let Trump go either way, and probably a Biden-packed court wouldn't have.

It's just another sign that modern Republicans aren't truly "Constitution-lovers" or textualists, that their leader is only safe because judicial activism invented immunity for him.