Monday on Twitter, writer Joss Whedon responded to a question from Kyle McManus. McManus asked the Agents of S.H.I.E.L.D. and Buffy writer for “Advice on writing strong female leads in a comic book?”

Whedon replied, simply, “Must value strength but also community and not have peeny/balls.” In what was likely a poorly thought-out joke, Whedon’s response was viewed by many as being steeped in transphobia.

“Whedon’s joke is cissexist in being based on the joke that ‘of course women have vaginas, duh,’ which is transmisogynistic since there are many women who do not,” writes Irae Nicole at io9. “His ‘joke’ insults trans women and intentionally or not, promotes misgendering us, which leads to discrimination and high levels of violence.” Nicole concludes by asking for an apology.

Whedon’s only statement responding to numerous calls for clarification on the matter came in the form of a tweet:

It seems, though, that Whedon has waxed philosophical on the topic of trans validity in the past, using the existence of trans people as a punch line in response to a question at Comic Con 2013:

“I have gotten [people saying I can’t be a feminist because I’m a man],” Whedon said last year. “How can you answer it? I can’t be a woman because I’m a man. Or, I guess you can, right? ‘In my day, we had to walk four miles through the snow to get transgender surgery and we were grateful for it!’ You know, I just don’t think that’s a valid comment. I think that’s a perspective I can never have.”