You are correct. The party knew what he was and did not care. Swalwell became a liability to the California Democrat Machine when the truth started dribbling out. The California Democrat Machine is cutting his throat. He like Joe Biden have become a liability, thus under the bus you go.
They don't care. Until now. They want Katie Porter to be the next Governor of California.
You are correct, he is a liability. California has a jungle primary and the current top 2 vote getters are Republican, meaning that there may not even be a Democrat in the runoff. The Democrats have to get Swalwell out of the race so that Gavin Newsome will at least have a chance of getting into the runoff (in which case he will win). That’s the only reason democrat politicians are turning on him now.