I don't think it is, to be honest. All three of those examples are clearly official acts. The President is commander-in-chief of the military, and is also responsible for granting pardons. The key piece of the ruling which lends credibility to her examples is that any motive or details behind the official acts are immune from scrutiny.
The only real difference is whether the acts are official or not. So the President is allowed to order the military to assassinate a political rival, but not to pay a private hitman to do so.
It's a pretty ridiculous and indefensible stance from the majority opinion.