2. I've seen it happen countless times. With the exception of pg himself, who displayed an allergy to politics or anything that got in his way of attempting to discover truth, I believe every HN moderator his sit firmly on the same side of the political spectrum and culture wars.
Being humans, most have a propensity to ignore inflammatory or factually incorrect comments they agree with while flagging those they don't as "generic" or flamewar inducing. I noted dozens of examples of this behavior but the ROI on going through them is almost certainly poor or negative. The moderation response related to major controversies of the past 2 years has been clear. Which pages were artificially weighted was very poorly correlated with the intellectual honesty of their contents.
3. I was indeed prevented immediately upon making the comment in my profile, and met with a message that I was commenting too quickly. Even after waiting a full hour, I was still blocked from commenting.
Interestingly another story recently asked about YC's GDPR compliance and was weighted so heavily that it sank below much older stories with fewer upvotes. Comments didn't outnumber votes, ether.
#3 is actually related to #2 as YCs deepening economic and political investment in an authoritarian state increases the likelihood of a future HN where comments challenging certain militaristic, ethno-nationalist propaganda will be flagged as "generic political arguments" while repeating the propaganda itself is allowed.
My view of YC's ethics is not so poor that I think this is an immediate risk, but money does tend to bend politics over time. In the early days, few expected Yahoo would one day assist in uncovering rights activists so they could be executed, and yet they did.