I would imagine that the reason for this policy, is that the moderators can't possibly do their job and moderate anything that they can't understand.

How do you enforce the rules about no comercial advertising, no cussing, no flaming etc if you can't tell whether any of that stuff is taking place?

If enough guys want to post in some specific language other than English, perhaps they could at least nominate one of their own to step up and perform (unpaid) moderator duties. That might convince Mark to allow it.