PA,
I experienced that on another site when I posted a link to Jill Stein’s platform. Got flagged, and then there was a nasty pile on. Was also flagged for saying it was nonsense to blame Nader for Gore’s loss in 2000, and detailed why. Was then temporarily banned.
So, yeah, circling the wagons definitely takes place in both wings of the duopoly. The Sanders/Clinton food fight made that abundantly clear.
Haven’t purchased Frank’s book yet, but have watched him on C-Span talk about it, and read a few articles from the book. I think he’s spot on about the Dems.