> Removing stupidity from a conversation on a private website is not censorship.

Is this not censorship? It sounds like you're assuming that "censorship" is by definition illegitimate or morally wrong, but I don't think this is inherent to the word (except to the extent that we still live in a generally liberal, pro-speech society). HN removing opinions from its boards seems like it clearly qualifies as censorship, even if you agree with the removal.

Removing “stupidity” on any platform, public or private, is absolutely censorship. And discussing any author bias is absolutely a contribution towards conversation surrounding the authors work.

by this definition of censorship, me asking a random person screaming in my house to please leave is censorship.

Author bias, alternative perspectives, etc. can all be contributions to meaningful discourse when they bring evidence or some meaningful engagement. Simply asserting your truth through circular logic isn't a contribution. It's not because the contribution is about 'bias' its because the contribution is stupid. Same rules apply even if think the person agrees with me. Process and structure trump content.

I'm saying this as the type of person who gets concerned when I see a stupid argument that arrives at the same position I hold, I don't get excited just because it's the same outcome.

> the idea that the universe started from an arbitrarily small size and expanded was once considered stupidity.

So was an idea that it was created by some supernatural being in 7 days. If you present theory without hard data - it's very rightly to call it stupidity.

Scientific process isn't free pass to throw random theories, without data backing them.

If by "agenda" you mean this:

> dire implications for the Covid-19 pandemic if it’s not brought under control soon through vaccination

then I propose a different target for the head-check.