It's strange that they haven't delegated to Congress to write a law specifying which acts are and aren't official, and that without said law, no acts the president does that aren't specifically listed in the constitution are official

That would be much more in line with the courts other decisions than asking a court to write the law

But if one overthrows the government via official acts, then one enjoys absolute immunity.

For example, the president can deem opposition party leaders to be terrorists and then in an official capacity order them to be assassinated by the SEALs. He can grant blanket pardons to everyone involved while he himself enjoys absolute immunity for his official acts.

The Senate will never be able to impeach or convict you when you’ve killed off those who would do it.

This ruling makes the president a temporary dictator, and it’s reeeeeally easy to go from a temporary dictator to a lifetime one.

A self-coup, also called an autocoup (from Spanish autogolpe) or coup from the top, is a form of coup d'état in which a nation's head, having come to power through legal means, tries to stay in power through illegal means.[1]

[1] https://en.wikipedia.org/wiki/Self-coup

Are you implying the president has complete authority over all branches of government?

It was an unsuccessful attempt. Apparently that's enough for you to be cool with it though.