You think Schumer is clever enough to spread this kind of narrative? I think he thinks that giving Mills a ringing endorsement and a few million dollars is pretty much all he needs to do, job done, on to the next wild success in Washington!
See my comment elsewhere about "the bad people." I don't think singling out the Democrats as the source of this is particularly accurate. I think the people who corrupt American politics and are actually skillful at this kind of thing don't much care whether it is establishment Democrats or Republicans who get elected, because they do fine either way, but they hate progressives and will try hard to defeat them when they come along. In general, I see no particular reason to think it is Democrats who are spreading this narrative. I don't think the people who are actually capable at this kind of fake news are foolish enough to get tangled up in partisanship in that way.