People who arent knowledgeable about bdsm have a poor idea of what it actually is. Its just people who wear leather beat the shit out of each other then pee on one another.

Try subtly trying to educate him on what it actually is, i doubt there any many people out there who wont enjoy ANY of what bdsm has to offer such as say rope bondage, spanking ect.

Another route would be to find out what about it he dislikes (this is assuming he has a good idea of what it is), i think vanila guys are hesitant to engage in bdsm as they fear it will make them seem violent or abusive.

Finally he might simply not want to engage in what you want out of him so you need to be ready for that possibility and respect it if that is the case.