Not a criticism, just something to consider...
One of the memories that stands out the most for me of childhood trips to Disney, Cedar Point, and other amusement parks is my dad and little brother calling me chicken, ride after ride, as they trotted off to be spun, flipped, hung upside down and flung through the air at the speed of light. I never - NEVER - minded waiting patiently while they rode. Never complained about having to wait. What I minded was the endless, "she won't go on that, she's too chicken, she's no fun, come on, just try it." It wasn't said in a cruel way, but obviously, it left its mark.
I now ride SM, BTM, and Splash Mountain, but I still don't go on the teacups. And the new roller coasters and virtual reality stuff? Forget it.
We've been to Disney with our kids three times, and my oldest (now a teen) has never gone on BTM, SM, ToT, won't even go on Splash Mountain. (she did, on the last trip at age 13, go on Goofy's Barnstormer)
She doesn't mind waiting. What can bring her to tears quickly though is an offhanded comment from her dad or little sisters about being "chicken" and "no fun".
So my advice? Leave him be. One of the things that draws us back to WDW again and again is that there is such a wide variety of rides and attractions, and that there's plenty for us to enjoy, even for us "chickens" who won't go on the speedy stuff. Unlike parks that are mostly thrill rides, I've never felt like the price for a day at WDW is a waste.
And you may find that, left alone, eventually your son decides to try a few new rides. A 12 year old has a pretty good idea of what he's up for, and it's not like he's asking for everyone else to skip the ride. (unless he is, in which case, a long discussion about respecting the groups likes and dislikes might be in order)
I wouldn't want anyone to "force" me onto a ride I was apprehensive about. And at the same time, I wouldn't criticize the rest of my family for being thrill seekers. We all get something different from WDW - one of the things that makes it such a great place to be!