I agree with some of the above and would add that 'making' someone do something is not the best way to go about things like this. You have to be aware that any level of forcing from you risks alienating him from the scene altogether - he is more likely to back away than enjoy anything.

Communication is a way to start and then start small - forums and chatrooms to start, then suggesting a munch and maybe some other 'apparently vanilla' activities with people who happen to be kinky - bowling, cinema, restaurants. In both the latter, general conversations would lead him to realise that these people are just like him - they dress in normal clothes most of the time, talk about their kids and jobs and the car and what they saw on tele last night and so on. Once you get that understanding, taking it to the next step should be easier. If that doesn't happen, at least you have some level of a social life with kinky people.

One thing that may concern him is that he may think he is too old for 'nightclubs' which is what fetish nights are percieved as sometimes (sometimes correctly but othertimes not). If he is over 30 this may well be the case and be the source of his reluctance.