Not sure many people would describe themselves as a tankie as in my experience it's used to mock people who ignore or deflect the atrocities the USSR inflicted on its people and the world.
As far as the other thread that people mocked, I think there's a place to say, compliment the Soviet space program while admitting that it was done under a horrible regime, in the same way you can say the same about the American space program.
Generally, I find whenever there's a vague superficial discussion about capitalism vs. communism, it's rare to actually discuss what both of them are, their strengths and weaknesses. More likely it's just mud slinging. For instance, is there something fundamental about communism which causes its people to suffer more than under capitalism? Are totalilitarian regimes a conclusion to any Communist revolution? Because really, that's what we end up talking about. Even staunch capitalists understand that exploitation of the labor force is by design in its system, but under capitalism is it required that racism be encouraged and even used by the people in power to keep its labor force powerless?
Pretty sure Marx actively discouraged proactively starting such revolutions even if he thought they were inevitable.