I would say if things go as planned with your travels/flight, you will be at Ohana no problem. That said, you hit the airport at 2, get in magical express line(or get your rental- would get to your resort by 3:30 if not much even quicker- even allowing a generous hour to check in (or simply give bags to bell services at hotel), and get on the monorail from Contempary to the Polynesian, I'd say you have time.
BUT of course any major flight delays, problems with magical express/rental arrangements/monorail delay- that could make it dicey. Probably won't happen, but it could.
Up to you, really- you probably won't be rescheduling Ohana any other day/time given its popularity- since its you and husband traveling, you stand to lose $20 on the reservation if you keep it and it doesn't work out. If you really love Ohana, keep the ressie, you will probably be fine, and if not you are out $20 which stinks but isn't catastrophic considering what these trips cost.