> The Stack Exchange community places a rather high value on "being nice." It's an important part of our values and we think it makes the Internet a better place.

OK. That's a fair viewpoint, also espoused by many open source communities for instance.

> A lot of the Math Stack Exchange users came from Usenet's sci.math where epic flame wars were the norm.

This, on the other hand, is kind of misleading. Is there some other threads elsewhere with material from Prof. Clark that is of the "epic flame war" variety? I ask this because I read Akhil Mathew's post in its entirety and even if you claim that Prof. Clark was not nice in his mentions regarding Jeff Atwood (a claim I highly disagree with by the way), his comments were in no way flame war material. So unless he's actually done this elsewhere, why even mention epic flame wars in association as it does nothing but confuse the issue.

> That community has a few members who do not consider "being nice" a requirement of public discussion, so naturally, conflict ensued when Jeff removed non-nice things (as is the norm in the larger Stack Exchange community),

I have to ask: Is referencing a person's own quotes in support of a valid position suddenly "not nice". This quite honestly reeks of removing comments that only Jeff Atwood (and perhaps yourself ;) finds personally offending. I understand from the thread that there is apparently some history between Jeff Atwood and Prof. Clark -- I still don't think that justifies the response given in this case.

> thus violating the "all public debate is sacred and must never be censored" norm of a small subset of that community.

I doubt that this is literally an actual community tenet even with professional mathematicians. The fact that they apparently permit citing relevant facts to support a point of their does not imply that they feel all public debate is sacred and non-censorable. Akhil Mathew quite clearly elucidated his position in my opinion, and I do not see where he claimed that Prof. Clark's comments should stand merely because they were debate. It seemed to me that he felt the comments should stand because they were constructive in nature.

> I think that the high norm for civilized discourse on Stack Exchange is one reason that it has such a high signal to noise ratio

Civilized discourse is certainly good for S/N -- but this is not uncivilized discourse from Prof. Clark by any reasonable definition!

> and it's why the mathematicians are on our site to begin with.

I'm sure the network effect of having other very high-quality associated sites with stable working backend software had nothing to do with that. ;)

> There was never any question of "censorship" -- the entire brouhaha took place in the META site, the site ABOUT the site... nobody deleted any comments about math on the Math site itself.

I hate to say this, but this is disingenuous. If you prevent someone from talking constructively about the site then you are censoring him. Sure you may not be censoring him from the main site, but let's not split hairs here.

As an aside I operate in a few communities that enforce a conduct policy... Prof. Clark's comments that were deleted would have been well within the bounds of decorum on any of those communities. You may want to ensure that your Stack Exchange values are being consistently enforced to avoid the appearance of impropriety, as the policies seem to be quite severe to me given the actions here.