If you take that argument to the logical extreme, a President who has committed all those bad acts can:
Stop all investigations of said bad acts, therefore avoiding impeachment.
Threaten any member of the House that is thinking of voting to impeach him.
On the off-chance is impeached and is now waiting the verdict of the Senate, have every incentive to offer all kinds of corrupt deals (free pardons, private arms deals, etc) to Senators to buy their vote. This way, they won't be convicted in the Senate and they can keep enjoying their infinite immunity forever.