While I do think Universal (and Disney) would prefer clarification on the contract, if there is the slightest chance of this happening, no way Disney Legal allows it to go forward. They would all be bounced from their coushy jobs, possibly even disbarred.
Also, not sure Universal wants to poke the bear too much. While 99% unlikely, a super narrow reading of the contract could put them in a worse place than they are now (for example, arbitrator says cut-outs not enough, you don't actually own Iron Man--just a hypothetical, but arbitration is free-wheeling, could go in any direction). Not to mention it would take years.
Finally, I still think Star-Lord and Gamora are fine, probably even Rocket. Building the ride with just them no problem. Advertising it between Miami and Atlanta--that is where the issue will come up.