It's Too Late (or will be) for the Democrats to Get What They've Always Wanted to get Through the Legislature - Punish Trump

Put simply, once a President is not longer in office there is no Constitutional language supporting the legislative branch punishing Trump

ARTICLE II Language

"The President, Vice President and all civil Officers of the United States, shall be REMOVED from Office on Impeachment for, and Conviction of, Treason, Bribery, or other high Crimes and Misdemeanors. "

ARTICLE I Language

"Judgment in Cases of Impeachment shall not extend further than to removal from Office, AND disqualification to hold and enjoy any Office of honor, Trust or Profit under the United States..."

"No Bill of Attainder or ex post facto Law shall be passed."

Since the President will no longer be in office he is simply a private citizen and removal is no longer possible and the Constitution precludes the legislator from Bill of Attainder (Legislative trials punishing citizens.)