I think what he tries to say is If you're a single man, then it means either you have never been married or have divorced whereas bachelor means you have never been married. But in both situations you are not married.
Okay, I'll try to do my best. Imagine there are three people called A, B, C. A and B are men whereas C is woman. In 2000, A and C were married but after having a lot of disagreements they have divorced so the person A is no longer married and is a single man now. But the person B has never been married so he has never had a wife. So the person B is a bachelor.