If you look at their past interactions with "tankies", they're all the opposite of what you say they should be: it's the "tankie" calmly and reasonably making their points while SoftestSaphic immediately descends into an incoherent raging tantrum.
If you're familiar with how the word "commie" was used during the cold war, its just an updated version of that, for people who don't want to sound like crusty boomers.