Anecdote time:

I'm currently dispassionate about racial issues, and can (and have) openly discussed topics such as the possibility that racial discrimination is not a real thing, the possibility that genetically mediated behavioral differences between races exist, and other conservative-to-reactionary viewpoints. Some of those discussions have been on lesswrong, under this account and under an alt, some have been on other sites, and some have been in "real life".

Prior to the age of ~19, I would have been unable to be dispassionate about issues of race and culture. I would understand the value of being dispassionate and I would try, but the emotions would have come anyway. Due to my racial and cultural differences, I've fended of physical attacks from bullies in middle school and been on the receiving end of condescending statements in high school and college, sometimes from strangers and people whom I do not care about and sometimes from peers who I liked and from authority figures who I respected. When it came from someone i liked/respected, it hurt more.

The way human brains work, is when a neutral stimuli (here, racist viewpoints) is repeatedly paired with a negative stimuli (here, physical harm and/or loss of social status), the neutral stimuli can involuntarily trigger pre-emptive anger and defensiveness all on its own. If your experience of people who posited Opinion X was that they proceeded to physically attack you / steal your things / taunt you openly in a social setting, you too would probably develop aversive reactions to Opinion X.

--

EDIT: just read the linked post. It independently echoes my account:

This is because respect for said arguments and/or the idea behind them is a warning sign for either 1) passively not respecting my personhood or 2) actively disregarding my personhood, both of which are, to use some vernacular, hella fucking dangerous to me personally.

--

The above is an explanation as to why it happens and how it is. I'm not saying it's justified, or that it aught to be that way. I made a conscious effort to fight down the anger and not direct it at people who were clearly not trying to physically harm me or lower my social status in a group. I think others should do the same.

For an extreme example, in the past an authority figure made a racial joke at my expense in the presence of other students who had previously physically taunted me, thereby validating their behavior - and I took care to not direct the anger at the authority figure (who was simply ignorant of the social status lowering effect of the joke, not maliciously trying to harm me). For a tamer example, I've never actually ended a friendship with someone for espousing certain views - I've only been angry and forced myself not to say anything until after calming down.

Currently, I don't feel emotionally angry at all when faced with those views, and i think every one else should strive to that. However, that doesn't mean that people who haven't faced this sort of thing are allowed to simply expect that people who have faced it will have that sort of emotional control. I'm pretty sure I'm an outlier with respect to unusually good emotional control (globally, if not on LessWrong) - most people can't do it. It also really helps that my current social bubble has less of that sort of thing.

That said (and this is where I disagree with the linked poster) I don't think it's a good idea to censor views for the sake of not triggering anyone's emotions. Dispassionate discussion of a topic unpairs the neutral stimuli with a negative stimuli - in fact, I would go so far as to recommend that people who are psychologically similar to myself (intellectually curious, emotionally stable) who have been hurt by racism should spend time talking on the internet to white nationalists and reactionaries, and people who have been hurt by sexism should spend time talking to pua's / redpill / the "manosphere". Talking about charged topics in settings where people are powerless to actually hurt you is a great way to remove emotional triggers.

That said, the small but vocal prevalence of meta-contrarian, reactionary ideology on LW has probably driven away a lot of smart people. There's even dirty tactics at play here - such as the down-voting of every single comment of anyone who explicitly expresses progressive views or challenging reactionary views. I myself am on the receiving end of this nonsense - every post is systematically downvoted by exactly -1 ever since I mentioned some biological evidence about sexual orientation that could be construed as liberal. I think our kind is so partial to contrarians that we actually give people a pass from the downvote simply because they went against the grain even when the actual ideas aren't especially insightful. Remember, well-kept gardens die by pacifism - reactionary ideas are fine if they are supported by real evidence and logic of the same standard you would hold if someone espoused a common viewpoint which is fairly obvious and popular. If it reads like pseudo-intellectual fluff, it probably is. Don't go easy on it just because it's contrarian.