I'm not certain on how the SC would rule, if a case ever made it there, on impeaching a president Or officer holder after they have vacated the seat.... I know it has been done before....
But in this case with Trump, he was impeached WHILE sitting in office, and not enough time for a trial before leaving office. The constitution says the Senate SHALL try those impeached....
That means the Senate, constitutionally, has to have a trial in the Senate....
The object of an impeachment trial is to remove a sitting president. Trump is not the sitting president, and can't be removed. To hold a trial now to remove Trump makes no sense.
That said, I hope that they hold the trial and it takes 2-months, then Trump gets acquitted, and runs again in 2024.
But it isn't just to remove from office, it is separately to Also decide whether the impeached person, can hold office in the future. You can be convicted and removed on 2/3s vote, then a 2nd vote, on whether to ban, from ever serving again in office, which only takes a majority vote.
An impeached person can be removed, but still be able to hold a future office....weird....but that's the case.... it is a separate vote.
Without holding the senate trial for an already impeached person, the 2nd vote, required by the constitution, on whether to bar from future office, won't have the opportunity, to be taken...is the argument.