When an addict tells you that you shouldn't use heroin because it will ruin your life, the fact that they used heroin and it ruined their life doesn't make them a liar, it make them experienced.
And the sole legitimate purpose in calling out hypocrisy is to get the other party to follow their own advice. But that means for Nazism and McCarthyism to be relevant you have to identify some specific present day instance of them that currently needs to be eliminated. At which point we would need to oppose that and what China is doing.
Especially when what really matters is academic credentials and not first-hand experience.
> WRT "currently", does Guantanamo count?
Sure. So let's oppose Guantanamo and what China is doing. At not let one derail every attempt to address the other one -- because stopping both is more important than which order we do it in.