This piece is terribly reasoned, with most of the logical errors flowing from a factual sleight-of-hand.

Trump was not a "former president" when he was impeached. He was in office. https://twitter.com/EVKontorovich/status/1355122935384711171

The Constitution unequivocally allowed to the house to impeach president Trump. Nobody disputes that.

The Constitution also unequivocally provides that the Senate SHALL try all impeachments

It's not discretionary.

Also, impeachment is a POLITICAL solution to a POLITICAL problem. There are some subtle signs of that in the Constitution, like, I don't know, the power to impeach being handed to one political body (the house, not a prosecutor), the trial to another (the Senate not the courts),

the punishments being entirely political (removal from & future bar on holding office) and expressly not criminal, etc.

The POLITICAL problem posed by an official committing high crimes and misdemeanors is twofold: what he can do in office now, and the specter of his re-election later. That's why both can be addressed upon conviction

Why in the world would (or should) the fact that one part of the problem was already addressed (he's in office), whether by resignation or the expiration of a term, prevent the senate from considering the other half of the problem?

And @EVKontorovich's parade of horribles about the potential for abuse? First, none of that applies to an official who was he impeached while in office. But also, the scope of Impeachment he concedes - any current official - can also be abused. The remedy is political

The house could impeach President Biden tomorrow, not because he did anything wrong but because they don't like his face. And the remedy for that would be people around the country voting out the bums who voted to impeach for stupid reasons

By the same token, if Congress decided to go on a spree of impeaching defenseless former officials for their crimes of 50 years ago, it's a remedy would be political. Vote the bums out

Bottom Line, This is a constitutionally indefensible take riddled with logical flaws. I am sorry to see it from someone like Professor Kontorovich