Is that a joke? Some women are such hypocrites when it comes to swallowing. Think about it from the opposite perspective. If you had a boyfriend/husband who told you that the taste of your juices disgusted him, that just the thought of tasting you made him gag and he refused to perform oral sex on you unless you had dental dam covering your entire genital region so that he didn't have to taste your juices at all.... you would have no problem with that? You wouldn't feel hurt or a sense of rejection? When men go down on a women they're lapping up their juices the entire time, any woman who can't manage to endure the 10 seconds of cum in their mouth is selfish imo. Intimacy plays a huge factor.
Edit - Granted, your bf didn't go about it the best way if he simply stated it like your title indicates, explaining why it's important to him would have been a more sensible approach but yeah.