You shouldn't worry about, him joking around with his friends about what they would do if they were in a relationship with a porn-star really doesn't affect you. I'm sure you are an attractive person, & i'm sure there are people who are even more attractive than you, that wouldn't change the fact that your boyfriend is grossed out by the act, all he implied was that if he was desperate/eager enough he might do it.

So i commend you for taking the mature route, sometimes there are things one partner is willing to do that the other won't. But the other redditors are onto something, we don't know much about your relationship but it is a bad sign if he takes something that he isn't willing to give.

Don't try to force him to change, that won't make anyone happy. Instead try to both discuss his concerns about the act, find out if it is a masculinity concern or a "disgusting bacteria" concern. Consider that the vagina is closer in form to an anus than a penis, it is a hole where things that men consider disgusting go in & come out (period blood, sperm, ect). Also try to make it more appealing, this means wash yourself thoroughly down there before you have sex, tell him it makes you really hot, ask him to try it once for your sake. Maybe he has a fetish that you can use, if he likes to be dominated then you can force him, he likes to see you orgasm so use that as an incentive, or offer him something in return for the first time (sexy lingerie night, a few blowjobs).

Good luck. Remember it is a share your concerns, show him this thread. A relationship means doing something you aren't always keen on for the sake of your partner, he should reciprocate.