SPOILERS ALERT - about the ending.

When it was finally revealed that, after the fright break warning, that it was actually a man, named Warren, who was pretending to be a woman who killed those people, my question is -

Why couldn't or didn't William Castle and the filmmakers actually make the antagonist/murderer a WOMAN and NOT a man who cross-dresses ala Hitchcock's "Psycho"? Did William Castle for instance fear a little too much that if it was really a woman who was a murderer then his film could be accused of being, whether at the time or otherwise, sexist or misogynistic?

But then again, there have been films at the time or even before that also featured female villains in them, right?

What do you think, thanks.