Well we've had this discussion on other grounds too, as you well know, but I think that since the language of the site is English, editing other-language typographical practices doesn't seem to me to be so out of line, especially if the question is already active. While it's true that it could be thought of as too minor an edit, and could be rejected on those grounds, I still think it's reasonable to accept the edit.
I don't think the analogy to British vs. American spelling (or punctuation) practice is relevant here, since those are both valid ways of writing in English, and therefore should never be subject to edits on those grounds.
One other consideration: we all consider it helpful to clean up grammatical and spelling errors in English since many users of the site are not native English speakers. And I think this help is generally appreciated by those users, since it makes their question more understandable to all. I don't really see why typographical practice shouldn't fall under the same rubric. I find it unlikely that a French speaker who puts spaces before punctuation out of habit of writing in French is deliberately using such practice when writing in English, just as they are not deliberately making any other kind of English error. This again is different from the case of British vs. American spelling conventions, which for some of us are quite conscious decisions.
