It's hard to understand why anyone gets up in arms with anyone online where there are ways to block and ignore people.

That being said, personal pronouns are an awkward thing linguistically. (Maybe they won't be in the future?) He. she and they are all pronouns recognized within English and have been for a long time. The farther you stray from those, the more likely you are to annoy people who have an idea of what language is in their heads. Those people could use a change of viewpoint of what language is - specifically that language is alive and changing - but transphobia might not be their real motivation. They're wrong, but not necessarily the morally bad kind of wrong.