They feel powerful after driving Zell Miller and the Scoop Jackson wing out of the Party, leaving George McGovern and Bernie Sanders.
No.
They're terrified that some true moderate might gain affection in the Rodent Party and split their barely stealable election successes.
They excommunicated Little Ralphie Nader after he took some 70,000 votes from Albore, who only needed 150 or so to steal the Floriduh electoral votes.
They practically nuked Jill Stein for her ill-considered audit of the Michigan 2016 vote, an audit which was naturally showing, as the Americans expected, that many of the precincts in Detroit were again showing that odd Rodent-Only phenomenon of having more votes than voters and those extra voters always go for the Rodent.
The last thing the Rodents can afford is a true party split, because they're already the true losers.