"The predators (rapists, stalkers, etc) are highly attuned and skilled at identifying WILLING victims."

There, fixed that for you.

"Hiding gender in that case could create a dangerous, false sense of security."

It's even worse. Exploiters and stalkers build a relationship with a delusion. Maintaining ongoing contact using a mystery persona gives their imagination free rein, ungrounded by contact with reality, building up a fantasy relationship that does not exist. The solution is to use your real persona, and end all contact the moment you start getting creepy vibes.