It allows for immunity to any "official acts" by the president while they are in office and does not define what an "unofficial" act would be. So if an action is challenged from the lower courts it'll end up at the supreme court where they will deem it official or unofficial.
Which brings the onus of dethroning a king president up to the Congress to impeach them. Which has never happened. However, we have impeached a supreme court justice in the past.