Neither the image posted nor “dismantling the gender binary” are feminist. And while the latter seems a worthwhile cause that deserved its own name and slogans, the former is a piece of art which echos hateful stereotypes about men and thus causes some.very real revulsion from viewers outraged by those stereotypes.
“they” has always been proper, it just used to be incorrectly taught agaist like split infinitives and ending a sentence with a proposition.
Wikipedia dates its first usge as over 500 years ago, and complaints less than 300.
https://en.m.wikipedia.org/wiki/Singular_they