One way of beginning to address that problem might be to use 'X is hard mode' as a schema for a lot of other things people have trouble talking about. It can also be agent-relative; 'sorry, eugenics is hard mode for me' is a nice stock-phrase alternative to 'sorry, I find eugenics triggering' (which might be objectionable if the 'trigger' isn't literally a PTSD trigger; or, if it is a PTSD trigger, the sufferer might not want to divulge that much). If the group of common 'hard modes' includes a lot of things that are more intuitively unsavory than 'politics', there's less bravado risk.

Though I don't think bravado is a very large concern, here and now and in practice. (At least compared to the kinds of things I tend to worry about re group norms.) Regarding politics, your comment is more cynical than my post; but regarding memes and conversation, I think my post is the more cynical. Neither of us trusts people to talk politics well, but I also don't trust people to talk about not-talking-about-politics well. So I suggested a meme that I think is useful, but also can fail gracefully in normal, everyday usage.

LW is not at risk anytime soon of falling in love with politics, but it is at risk of appearing arrogant, dismissive, insulting, thoughtlessly-opposed-to-local-politics-and-groupcraft, etc. Its most widely used memes should probably be useful for outreach and for teaching new ideas -- people get exposed to LW through sloppy, improvised conversations, at least as much as through carefully crafted blog posts -- not just useful for making known facts more introspectively salient to people who already know all the fundamentals. (Of course, it'd be nice if something served both purposes.)

I can see 'politics is the mind-killer' being fairly useful to a fan of Dune who's familiar with the heuristics and biases literature (especially confirmation bias, sophistication effects, motivated reasoning, bias blind spots), has read some of your and Eliezer's writing about politics, and is entering the discussion feeling extremely friendly, sympathetic, and non-defensive. That's why I mentioned that 'politics is the mind-killer' might be a useful internal mantra, like 'politics is SPIDERS'.

But I don't think spiders or mind-kill is a useful meme for people who haven't internalized the sequences. (Including people on LW; 22% of people who took the last LW survey said they'd read at most ~25% of the sequences.) 'Mindkill' is likelier to make people authentically mad than authentically scared; if it makes them scared it probably won't be for the right reasons; and when I run mental simulations of chatroom or meet-up conversations, I have an easy time envisioning a conversation that's starting to go off the rails staying unproductive, or getting worse, because someone said 'you guys are getting mind-killed!' or 'psh, don't you know that politics is the mind-killer!'. (And people who've actually overheard the term seem often to agree with my impression.)

Maybe we aren't disagreeing bigly, but are primarily intuiting different typical usage scenarios for stock LW-isms? Mental mantra and Secret Word of Power, v. something you throw out in mixed company or use to convey new information to someone. I envision "politics is hard mode" serving a social role more than a mnemonic one, to guide conversation and show newbies the ropes. It's OK if it doesn't try to encode an explicit warning 'ALSO HARD MODE IS A LOT HARDER THAN YOU THINK, AND PEOPLE CAN DIE, AND AHHHHH', because the way the mantra is being used (to pivot the group away from a political discussion) conveys that information, plus people can optionally talk about all that stuff when it's strategic to do so, but eschew bringing that point up if all they really want to convey is 'politics is epistemically hard; let's do something easier'. Cutting memes up into their atomic sub-ideas is useful for mental focus, but also for incremental pedagogy.

It's the sort of thing that could work on someone who hasn't heard the idea 'politics is the mind-killer' before, or has heard it but hasn't fully understood it, or understands it but doesn't fully agree with or accept it. I'm interested in talking to at least some of those people.