The only reference I can find from them "impersonating" a feminist is this https://github.com/search?q=FeministSoftwareFoundation&ref=s..., which references the user https://github.com/AndreaDworkin

Since Andrea Dworkin died in 2005, I'm not sure how she could have a github account today, so the "impersonation" claim might be a little thin. I think it would be akin to creating a github user called "ErwinRommel" or something -- referencing a well known person who isn't around any more.