Considering that an ex-president who invaded a country under a proven false pretext and in violation of international law and has a million Iraqi civilians on his conscience is still painting his little pictures in Texas, perhaps the Supreme Court decision is not as big a break as some seem to think?
One could at least argue that the Iraq invasion was within what was generally understood to be the role of the president at the time, specifically leading the military as its commander in chief. No one expected throwing a coup to be within the normal role of the president, but apparently that's also covered according to this decision.