In this case, it's not about "should factual discourse be allowed or not," that's a false dichotomy. It's whether the author of the memo knowingly took an approach to interpretation of the "facts" he selected that was actively harmful to his co-workers by creating a toxic and hostile work environment.

I believe he did, and the parent you're responding to seems to as well, but they didn't say anything about "spar[ing] factual discourse." You seem to be reading that into their comment.

And I would definitely say there are factual discussions that can be had privately between individuals who already trust each other that are better kept private in order to spare the feelings of non-participants. Other humans have feelings, taking them into consideration is not weakness.