Heh, heh . . you don't want to try to discuss anything with them. As soon as you posit fact(s) they resort to name calling and most of "Alinsky's Rules for Radicals".
Arguing with a liberal or worse, a self proclaimed "Progressive" is like trying to stop an avalanche with words . . And if your facts cannot be rebutted they usually do exactly what you've described. Banishment.
Liberals preach "Tolerance' but that only goes as long as you "Tolerate" their agendas. When you push back, you're either a Racist or other "Non Tolerant Radical" who's not "Politically Correct" (Neither correct nor tolerant).
Screw 'em . . Just read about their dumb-assed ideas and agendas and tell those who can or will make a difference . . There is nothing to be gained by arguing with an Idiot . .