“You either have law, or you don’t.”
I have heard where some of the talk-show people and politicians think bringing him up for impeachment now would help the dems in the fall and perhaps in 2016 (sympathy, portray the repubs as out to get all dems, etc.). And they make some fair points.
OTOH, you make a great point - not bringing him up on it is just playing politics. Treason is a serious matter not to be trifled with in playing games. Although one could also argue that one is “doing the greatest good for the country” by playing politics with it to win the next election.
Just like Nixon could have legally gone through the impeachment process, and I’m not sure, but I think he thought he had a chance. But instead, he resigned “for the good of the nation.”
Nixon resigned because congressional members of his own party, led by Barry Goldwater made the walk to the White House, and told him to resign or he would be impeached, and removed from office.
At this time there is not one Congressional Democrat that would consider making that trip to the White House.