For myself, I personally think it crossed a dangerous line when Obama killed that citizen without a trial. I also think this SCOTUS is corrupt and this ruling is dangerous.
That's the same lukewarm sentiment that he's always received. It was an impeachable, criminal act.
My point is that he got away with it anyways, even without this "official act" clarification. Which just goes to show you that people whipping themselves into a frenzy about this have not been paying attention. They're using the most extreme language ("Seal Team 6 assassinations!!!") to describe some hypothetical that has already occurred without this ruling. It's silly.
Why are you upset that people are concerned by a ruling allowing exactly what you're concerned about? Shouldn't you be upset that neither the DOJ nor Congress took action against the President in question?