He'll be well taken care of at any Disney owned TS restaurant. I'd look over the menus to be sure that there's something on the menu that should be easily modifiable (as in leave off sauce, bake instead of fry) that he'll like when booking the ADR.
For CS, I'd recommend the following locations if they want to eat CS in the parks.
MK: Cosmic Ray's
EP: Sunshine Seasons
DHS: Flame Tree BBQ
DHS: I'd eat TS
There are other places that do provide allergy foods but they all have fries as their side and the fries at WDW contain soy.
We prefer to do TS in the parks and CS at our resort. Resort CS has a lot more options than park CS. In parks, you're limitted to the premade items. At resorts, chefs can customize something safe using whatever fresh ingredients they have on hand.