Just a couple of things--

45 wasn't impeached as a sitting president. the house voted to impeach and that died once it got to the senate.

Belknap wasn't impeached either-- the house voted to impeach and the senate couldn't muster up the 2/3 majority. He was acquitted.

The difference here is that he resigned while the impeachment process was taking place. The senate continued the process after he resigned.

The rules aren't vague when it comes to a private citizen.

I do agree that this is a colossal waste of time