They're actually not exclusively talking about Hussie. I believe Gio was involved with harassing a trans woman named Kate Mitchell who was a writer for Homestuck. Which is what most people mean when they say Gio has a history of being transmisogynistic. Also, Andrew Hussie is non-binary. People can use whatever pronouns they want for Andrew Hussie, but to ignore this fact about her is silly. You just assume because Andrew Hussie is more masc presenting that no one can be trans misogynistic to them. This is not true. It is also a lil weird to brush it off when multiple queer women who do work for Homestuck have stated they don't exactly feel comfortable with the way Gio talks to them.

Also Pronouns =/= Gender. A person can very well prefer He/Him and also still identify as a women, and vice versa.