Apologies to the mods.
I think the best evidence that "tankie" is a meaningless snarl word is the way the people who use it just make up what ever positions they like to ascribe to the mythical "tankie". Like, none of the people you call "tankies" support modern Russia, but you're going to insist that tankies support modern Russia anyway, because it's not meant to an actual descriptive word, just a way to punch left.