Every time a character in anime and manga who uses atashi causes gender drama in the western fandom, I age 20 years.

Atashi denotes politeness, a sense of refinement or glamour, or an old fashioned attitude. It is also gender neutral, with both men and women using it. Gay men and older straight men use it as well as women. The reason it has a "feminine" reputation is mostly because it is part of polite speech, and it is less acceptable for women in Japan to use casual or rough speech compared to men, so inevitably they end up being polite more often.

I don't know this character or anything to do with Jojo, but them using atashi is not the gotcha that fans think it is.