Earlier quoted context omitted.
That's complicated, but not actually unexpected. The Constitution lays out the process and authority to check the President's power, and that process flows from Congress. SCOTUS essentially said "If Congress didn't even find a violation that moved them to invoke their maximum penalty of removal-from-office, why on Earth does anyone think we would impose the law to punish the President's official actions where Congres…
I get what you're arguing but isn't "Jail the President for doing Presidential stuff" a bit charitable? "Nope, don't see it" isn't so simple, I think a lot of people would argue that this follows from the rule of law set down in the constitution in the form of things like the supremacy clause and implied by our entire legal/political structure.
One of our Presidents, against the will of Congress and in an era where the right to levy war on the part of Congress was far more closely tied to troop deployment (because we weren't yet in the era of Pax Americana with permanent overseas bases on every continent, much less the post-9/11 era of massive power delegation to the Executive), moved our Naval assets away from the Atlantic coast toward Europe and basically tried to hide it from Congress. It would have been extremely impeachable... But then we ended up in a World War soon after. A war we, conveniently, already had our Atlantic assets positioned to fight, over the previous desires of an isolationist American representative legislature.
That President never came under question of whether he should be jailed for putting Americans in harm's way when we were not involved in the European conflict (yet), and Congress had no intention of involving the country (yet). The things Trump did in office were far less risky to life and limb. I'm not implying they were correct or just things; I'm saying that when we talk about whether the other branches should be able to jail the President for malfeasance in-office, this is the realm of decisions and standards we're talking about.