If you have crutches I'd suggest just bringing your own, or taking a quick detour to a drugstore (if you can) and picking up a pair there once your on your way to your resort.
Otherwise I'm sure you can rent them if you need to from some offsite rental companies or look into a EVC if he needs it. I know being on crutches is hard on the body, I couldn't imagine using them all day in a park though I can see using them to get around a resort if need be.