Maybe, but casually throwing out an accusation like this without supporting evidence is reckless at best. I would downvote this comment if I could.
Update: Found this old HN thread https://news.ycombinator.com/item?id=16726998 with vague recollections of certain encounters on the bug tracker. My takeaway is the maintainer(s) didn't put too much effort into understanding some bug reports (not good but doesn't deserve the "abusive" label) and was perceived as rude (which in my experience could sometimes be attributed to lack of tact from non-native speakers). So, hard to conclusively tell without more concrete evidence.
I can back this up. It's well-known that Fox is not a nice person. See [0] for previous discussion, or just browse around the old TT-RSS forums (warning: some mildly NSFW stuff there).
edit: Regarding your edit, no, it isn't a language barrier. He's quick to insult people and treats feedback/contributions as opportunities to feel superior or meme (e.g., [1]). It's like talking to 4chan.
