Moscow Mitch has nothing to do with impeachment. That is Pelosi's, Nadler's and Schiff's domain.
Where Moscow Mitch comes in is whether or not he will try to stop Articles of Impeachment being actually taken up by the Senate for a formal trial. He knows full well that there is no way 20 of his Republican Senators will actually vote to convict and remove from office, even if it is proven Trump bit off the heads of all their first-born. But he also knows that an impeachment trial could bring a LOT of ugly Republican dirt out from under the carpet where they have been sweeping it ever since the 2016 campaign. If he stops it from ever coming to the Senate (not for sure that it would be legal, but that has never stopped him before), there will be a huge "what are you trying to hide?" to counter the ever-weaker "witch hunt" cries from the Republicans. If, on the other hand, he "does his duty," and lets a trial take place, he risks SO much ugly stuff coming to light that he might damage Republican Senate, House and statehouse chances for the 2020 elections.
The way I see it, McTurtle is worse off if he lets the impeachment trial take place, but might be in such legal hot water if he tries to strangle it before it comes to life that he might find himself the subject of highly uncomfortable proceedings himself. He might find himself forced to resign, and I think he sees himself going out retiring in a blaze of glory in six years, not running away in shame and leaving his seat to Amy McGrath by default. Maybe Matt Bevin can try for it?