As another commenter mentioned, would it have been appropriate for him to direct a question to "the black CTO"?
Really, the fact that this is even being focused on as sexism is crazy. In much of the world women are actually being brutally oppressed, and I would assume that the overwhelming majority of people involved in complaining about minor events like this have not and probably never will do anything to address that. So do they really care, or are they just virtue signaling?