There's also no reason why the phrase "suburban-bred office cow" can't refer to a man. The word "bitch" is often used to describe an emasculated male, so this use of "cow" is not without precedent.
I'd agree with the precedent. I would classify a bullock (castrated male cow) as a cow not as a bull. Equally I'd classify a man with (figuratively speaking) no balls a 'bitch', or a 'ball-less wonder'.