Ah, it looks like we interpreted his words differently, and I misunderstood what you meant. I assumed that
>I cannot work with a woman without thinking about having sex with her.
meant that he can still get work done with women, but he thinks about having sex with them.
I should also clarify my point "that many of my platonic female friends are very attractive, but I don't want to have sex with them." I'm not saying that the thought never crosses my mind, just that it's not an issue.
About your last sentence, if I apply it to my situation, the first part is true. There has never been a time where I've been with them, but the thought has never crossed my mind, but I value our friendship, so I have no reason to try to act on that. I believe your point is that coworkers are more of an issue than friends in a situation like this, and I completely agree with that, but I just don't think it's necessary to see a therapist until he does anything more than occasionally staring.
He seems obsessed with the problem and and can't cope with the guilt of his own thoughts, he should see a therapist to learn about how to deal with that. To say someone to see a therapist is not an insult! It's mental health, it's fine!