There is a difference between people advocating for human rights abuses and people saying that some actor does in fact not engage in human rights abuses. The difference is stark and even there, if the actor would in fact in engage in human right abuses.
An open society must tolerate the later. I.e. we must tolerate that people dispute that human right abuses occur or occurred. This is because you cannot judge someone purely due to getting the facts wrong or not knowing them.
If we wouldn't allow this, we would de-facto argue for a totalitarian state, since we wouldn't allow people disputing facts (which can be proven or disproven). We would have to nominate some entity that judges what is fact and what isn't, which is the opposite to gathering evidence and engaging in an open, society wide discussion.
To be clear: Allowing discussions around whether abuses occur is notably different to letting people get away with advocating for abuses. The latter is what needs strong responses. The former is what requires engagement.
I don't see anything on lemmy or in the mastodon thread that shows that human rights abuses are advocated for. What I do see is that there are some fractions that show sympathies to China which you would otherwise only see for the USA. I think its useful to compare these sympathies because they seem to express themselves in similar ways.
With all that said, I think the opinion expressed in the mastodon thread is not particularly useful. It, in many ways, minimises real human rights abuses that occur world wide, day to day, in China, USA, and many other countries in East and West.
Let's call out the abuses, let's discuss and present the evidence for them, let's not alienate people and create polarity that looks like us-vs-them.
I think the problem people see is more with creating an equivalence of political opinion and mental health.
The full quote about anti-capitalism doesn't say anything about what makes someone an extremist. It doesn't say anything about rational criticisms and irrational ones it just relates political attitudes. It doesn't say anything about how we would separate rational criticism from extremism. That is a problem, no?
The take home message doesn't help at all when a dissident deals with an oppressive system. E.g. how would that message be applied in Germany in 1933? Or 1939? Or 1942? I don't think it can at all. How would it be applied to say US intervention, or colonisation? Again, I don't think the message would hold up.
Do you think that the scientific method is applied here in an appropriate way?