While published lists are good, everyone's "pain" is different. Location of pain, type of pain (sharp, stabbing, burning, constant, etc), the person's tolerance, how dependent they are on pain meds, and other factors play a role. In addition to what happens during a ride, you need to also consider the "what if" scenario? What if the ride has to come to a sudden, unexpected stop? Even the teacups could jerk you around a LOT if it comes to a sudden stop. And the raceway at MK, while not a jerky ride, is murder at the end of the ride when cars are stacked up waiting to be unloaded. You are
guaranteed to have someone bump you very hard from the back.
There is so much more to Disney than rides. I've gone on solo trips and rode only 2 - 3 rides during my entire stay. Shows, streetmosphere, and other activities can fill your days. Going to a park to catch parades, fireworks, etc. is fun. I find EPCOT to be a full two-three day park if you try to catch all of the different shows in the countries. Visiting the resorts is also cool. Sit in the lobby of the Grand Floridian and listen to the pianist, sit in the viewing areas at the Animal Kingdom lodge and watch the animals. Or maybe afternoon tea? If going before the end of this year-La Nouba.
All that said-here is my list of "able to's" (off top of my head-I may miss some): MK: Pirates, Hall of Presidents, Liberty Belle, Haunted Mansion., Peter Pan, Small World (the boats sometimes bump but nothing major), Pooh, Voyage of the Little Mermaid, Buzz Lightyear, Monsters Inc Laugh, and a MUST DO-The Flag ceremony, parades, shows, street shows like Dapper Dans, pianist at Casey's etc. Just for kicks-may he'd like to have a haircut at the MK barbershop. EPCOT: Everything except Mission Space, Test Track and maybe Spaceship Esrth (it rattles); AK_I don't even go. While there are lost of non-rides things to do, they all involve animals and I just don't care. The Safari is horrible-I don't care where you sit. I've been everywhere and come off in pain-it usually goes away after awhile.Studios: everything except for Star Tours and Toy Story Mania-TSM whips you around corners.
If you have time and are able, you can be his tester. When a new attraction opens, my SIL will ride it and get off and let me know if I can handle it