I haven't seen it, but there is the new Goofy's Dancin' Jamboree at the Diamond Horseshoe, also the Enchanted Tiki Room show, and Tom Sawyer's Island (the raft trip over is not really like a ride). Also, at Toontown you can visit Minnie's House and Mickey's House....not rides, but lots of things to look at.
At Animal Kingdom, there are a lot of paths to take to look at wildlife, and if he will take the train ride to the Conservation Station, there is a petting zoo, also displays to look at (incuding one that lets you control video cameras to look at different animals in their barns and out in the open). Also, there are several shows....Tarzan, Flights of Wonder, Lion King and Pocahontas. And look for the acrobats in Africa....they are jump rope, jump through hoops, do the limbo....they are amazing.
At Epcot, The Land boat trip is very sedate. At the Living Seas, you can spend time watching the fish (look for times when they will be feeding or when there will be special presentations). Also, at Innoventions, there are interactive video games (the kid is in the game...they put on a vest or belt that has sensors on it, then depending on the game, they do something that controls what happens in the game (if they hop from side to side, the character on the screen hops from side to side, if they jump, the character jumps). And in the World Showcase, he can do the Kidcot Stations and also there are a lot of street performers that are fun to watch.
There is lots to do....and you never know, you may get it all planned out and then he'll get there and see rides that don't look terrifying to him, and he'll want to spend all his time on them!