Did Sony try? I've never heard of that before (but then again, I'm not familiar with PSABR's development at all) Do you remember the interview on hand?
I can see DIsney being against fighting games. But if there's a fighting game Disney (might) be okay with it's going to be Smash Bros., IMO. No blood, very cartoony. The roster doesn't feature anyone like Kratos....I'd actually be okay with Mickey in Smash.
What happens if it was just Sora -- no Goofy or Donald? Would Disney still have a say in it? It'd be weird to have Sora without Goofy and Donald though; so he's probably unlikely due to copyright issues.