It makes no sense. They even say why in the movie -spoilers-

When Douglas first visits his lawyer, she says the key of all this issue: harassment is a question of power.

It's not that a woman can't harass a man. It's that an employee can't harass his superior. It's the situation of power, the fear of losing a job or not to be believed, what makes the victim defenseless.

Demi Moore was THE BOSS. She couldn't be harassed. She could have been raped, offended, and many, many things. But not harassed

The whole movie is built on a false premise. Does the book fall in the same mistake?