It is just like women who hate men.Hating women is something I have a hard time getting my head around but definitely exists. I can see being angry with an individual woman as you can be with a man but to just be angry with all women is so counterproductive if you are a heterosexual and want some action.
Think of it more like a resentment. Both feel the need for the other in some way and hate the fact that the other side has the control.
So for him, it could be he needs women for sex and resents all women for the pussy power he believes that have. That then morphs to co-worker being an ugly bitch with no real experience in his eyes. We don’t know her side of the story and it could be vastly different from his because he is not quite living in reality but in the resentments he has made against women.
This is speculation. I have no idea if it is true. It is just and example.