I think Joseph’s post here (sorry Joseph!) highlights one of weaknesses of the CF and similar discussions elsewhere. In particular, people tend to post essentially made-up things.
Perhaps Joseph could have written something more thoughtful along the following lines. Although a braisa in arvei pesachim states that אין שמחה אלא בבשר ויין, that is already qualified as being only בזמן בית המקדש (ועכשיו שאין בית המקדש קיים, אין שמחה אלא ביין are the words in the continuation). Even on shabbos, which you probably would also call a seudas mitzvah the Shulchan Aruch HaRav (242,2) wrote that there’s no chiyuv to have meat if one does not like meet.
The Maharam Shik (AH 89:2) actually writes that one is actually chayav in basar at a seudas mitzvah, but it’s not clear that this is universally accepted. In fact by a bris milah, which most probably believe constitutes a seudas mitzvah, it seems that many kehilose had takanose that they davka not be fleishig, and only include fish, because of the high costs. Of course if there was a real chiyuv to have meat such takanose would have been meaningless.
Of course Joseph can offer other perspectives, but blankly stating “A seudas mitzvah should be fleishigs.” doesn’t really contribute anything to the discussion. Indeed yid18 was just asking what people would prefer. For the record, if it’s at dinner time I’d probably prefer fleishig, unless I had had many fleishig meals that week in which case I might prefer milchigs.