Didn't the Supreme Court declare anything the administration does, legal..? Or was that just for the president?
It did not declare that the president cannot be impeached. It did not declare that the president cannot be criminally charged for what he does that exceeds the scope of his office (though it's a high bar to prove it). And most of all, it did not declare that whatever he does is automatically constitutional.
He could order the assassination of rival politicians for national security purposes and we would get a 6-3 ruling that nothing can stop him except the GOP congress.
No.
> Or was that just for the president?
Also no.
It established a three-branch approach to whether the President is immune to criminal prosecution for acts that, ignoring any immunity he might have due to being President at the time of the act, would be within the domain of potential criminal prosecution, in which (loosely):
(1) Acts relating to a narrow set of core Constitutional powers of the Presidency are given absolute immunity,
(2) Other official acts have a case-by-case analysis for immunity weighing whether allowing prosecution for the kind of act involved would impair the functioning of the office,
(3) Acts that, despite being committed while President, have no official character have no immunity stemming from the fact that they were committed while President.
One must understand that the more safeguards we have to enact retribution in these cases, the better. You're not supposed to point to one after loss of another - you're supposed to point towards as many as possible. Before last July, the courts were the one we pointed to the most, and they are no longer nearly as much at our disposal as they were before then.
It doesn't invoke sovereign immunity through a loud roar, but from an understood nod.