I really respect your view, and there's a lot of truth in it. Here's my perspective:

The USSR was a state whose existence had an overwhelmingly positive impact on the lives of it's citizens and the broader cause of global liberation. Stalin was a leader whose actions had a positive impact on the direction and strength of the USSR. The Molotov-Ribbentrop Pact was a rational move by the USSR, which made sense under the assumptions held by Soviet leaders. Most importantly, it was certainly no indication of sameness between the Nazis and Soviet's, and attempts like "black ribbon day" to label it as such are as disgusting as they are wrong.

But, even the USSR and Stalin made mistakes. The assumption held by Soviet Leadership that they would benefit more from the pact in the long-term was correct, but they failed to anticipate the possibility that Hitler would use the short-term advantage it granted to fulfill his genocidal vision as soon as possible. Similarly the assumption that by fulfilling their end of the bargain (even as Germany's commitment to it's terms began to falter) Germany would be less inclined to invade them turned out dead-wrong. If nothing else, the lesson of the M-R pact should be that if you're the leader of a socialist state; never assume that anti-communist forces are rational or trustworthy, really, expect the worst and you'll never be disappointed.

I would never signal boast Ericson or relay his perspective to non-leftists, in the same way I wouldn't spend my time loudly proclaiming failings of the USSR, or other socialist states, to liberals. But I feel comfortable in speaking about the the (mostly understandable) mistakes of past socialist states on this site precisely because most here are leftists and already support the same causes and end goal which I do (yes I'm including anarchists and communists here. We're all fighting for a stateless, classless society). They just disagree on how to get there, and I believe that it's generally positive to learn from the past to see what worked, and what didn't. In my view, the M-R pact was something which didn't work, and lessons from it can be applied today, and perhaps even to the topic of this thread.

Now I'm aware that nothing I do or say will change anything that China does. But I believe that when comrades are discussing what they perceive to be a mistake made by the Chinese state, there is value in bringing up a relevant historical example of something similar which occurred. To add context if nothing else.