I was pretty similar, in that I wasn't feeling all that jazzed about all the different events. I wound up going to all the events at the encouragement of my family and friends and actually wound up having a pretty good time. All Night Grad in particular was basically a carnival and very fun.
If he has lots of friends that also don't want to go, would you consider hosting something at your house the night of prom as an alternative? Junior year, instead of going to Prom a bunch of us went to Kings Dominion, which could be another option. There were also a few years where for homecoming, I got dressed up, took pictures, and went out to dinner, but didn't go to the actual dance. So we have the fun fancy pictures and a fun meal, but without all the gross sweaty dancing. This might have been more fun for me as a girl than it would for your DS, because for me just the act of getting dressed up was pretty fun, but I threw it out as an option just in case
