Actually, this user has been posting in this thread for months - the earliest post I saw was in January. The user posted several times asking for updates as to whether this feature was planned or not, fairly politely it seems to me, and was totally ignored as far as I can see.
After repeatedly asking for updates and having no response whatsoever, it seems they became disillusioned. Which I think isn't unreasonable - it's my opinion that it's pretty rude for a maintainer to ignore reasonable questions put to them, and that it's quite reasonable to be offended when you are ignored in this way. You talk about "aggression", I say ignoring people is an act of aggression, and it seems to me that this user has simply responded in kind.
We could get into a discussion on whether a maintainer has any responsibility to respond to users asking questions, and then use that as a basis for deciding whether specific posts by this user were justified or not, but my point is that the picture you paint with your post is inaccurate and incomplete. At best.