The mind killing bit makes sense, but wouldn't you want to combat it by confronting it head on and refusing to succumb to the polarization? I don't find it to be particularly hard to do, and I'm fairly certain I haven't been mind killed.

Discussing mindkilling is difficult. I also wish there was a way to discuss politically heated topic safely (even at the cost that I would be forbidded to participate, just allowed to read a discussion on topic of my interest written by people I consider rational), but seems to me that experiments don't give us much hope. Even on LW when the discussion starts to approach something political, I feel it becomes worse that usual, though still rather good compared with the rest of Internet.

It is difficult to argue why and how exactly this happens, because saying "a person being mindkilled usually does not feel like being mindkilled" seems like a fully general counterargument. But in my experience, someone saying they are able to discuss topic X without being mindkilled means almost nothing. I believe some people are able to discuss some sensitive topics without getting mindkilled, but I also believe there are much more people who think they are able to discuss the same topic without getting mindkilled and they are completely wrong. Trying to invite to discussion only people self-diagnosed as resistant for mindkilling does not work.

If such discussion ever becomes possible, it will need to have very strict rules set in advance, much higher than an ordinary LW discussion.