The whole place is a giant sensory overload so if you've got a seeker he'll be in heaven.
Check height requirements on the rides on the lowest level. I don't recall if there are any or not. I doubt a 2 year old would put up with the helmets on the Aladdin ride. The river raft ride would probably be fun since it moves back and forth like you're rolling down a rough river and there's even a touch of spray. If there's no height limit on the Pirate game then if nothing else he can watch the screen and point out ships to everybody if he can't get a good grip on the cannon (it's like the TSMM shooter).
The video game areas are probably not going to hold much interest unless he's a visual seeker and will be happy watching all the activity. There are a few video games that involve sitting inside a vehicle or in a seat and steering so if he's with somebody else he could probably have a ball doing it. It's all very stimulating.
I'm not sure what else a 2yo could actually do in there, sensory issues or not.
If he occasionally needs a quiet place to decompress (even seekers can only take so much), go all the way to the top floor. There's a food counter and a whole bunch of seats themed like Alice in Wonderland. The colors are deep, the lighting isn't as bright, there are some booths, and it's typically the least crowded area of all of DQ.
I honestly have no idea about the stroller as a wheelchair. I was told that a GAC can't be used there but I don't know if that tag would be the same.
Don't go on a rainy day. Lots of people see an indoor attraction as a great place to go on rainy and/or cold days so it's much more crowded. We went mid-afternoon on a hot (upper 80s) sunny day and it was practically empty. It was WONDERFUL.
