trolls like sam and his "I can't say things, because you politically correct morons will downvote me into oblivion, but be sure that my arguments would be crushing, if I was allowed to make them, which I'm not, therefore I'm not making them" style of debate.

Sam dosen't do that. Sam trolls by stating his opinions fully. He then refuses to provide evidence.

If the issue is e.g. whether science seems to indicate that the statistical distribution of physical and intellectual characteristic isn't identical across racially-defined subgroups of the human race, or across genders, or across whatever, then it can be discussed politely, if the participants actually seek a polite discussion, instead of just finding the most insulting way possible to talk about them.

Race differences have already been explicitly discussed with little problem, if not prominently so, do a search. Gender, sexuality and sexual norms are the great unPC problem of LessWrong.

And if the participants are willing to use words like "average" and "median" and "distribution" and things like that, instead of using phrases that are associated with the worst metaphorical Neanderthals that exist in the modern world.

Dishonest generalization, find two posters in addition to Sam who do this. I will wait.

Now contrast this to the average (even average anon double log in account) pro-hereditarian LW-er who brings up such points. There are far more Quirrells than Sams here, and Sams get heavily downvoted except on the rare occasions they make more reasonable posts (though the particular poster has probably burned out some people's patience and will get downvoted no matter what he says because he has consistently demonstrated an unwillingness to adapt to our norms).

This is quickly devolving into the worst kind of politicking one finds on otherwise intelligent forums.

What I think enflames things far far worse is when people imply that you are incapable of discussing topics, but nonetheless hint at them. If the topic can't be discussed, then don't discuss it or hint at it at all.

But it is other people who keep dragging them up and discussing them. Politely stating that you disagree and they are wrong, getting then heavily up voted (which indicates a significant if far from majority fraction of LWers agree with the comment) is surely better than not interrupting what you see as a happy death spiral?

If it can be discussed, then discuss it plainly, clearly, politely; not trollishly or deliberately offensively or carelessly offensively

Have we been visiting the same forum? I have often up-voted your responses to Sam0345's posts, indeed you nearly always successfully rebuke him. But I think your extensive interactions with him may be leading you to mistake an individual for a group.