Not that we mind walking, but do you have to take a taxi to the Contemporary, then walk, or can a taxi bring you to MK? We haven't been in several years and only did Busses to MK. We also have an early BOG ADR and plan on getting a taxi.
One story to reinforce to your DH a good reason to rent a cab, on our last visit we were over an hour late to a ADR for Ohana, which was recommended by some friends and the only restaurant that I especially chose, wife chose the rest. We had spent the afternoon at the POR pool and asked a CM and found the best way to get to the poly was via bus to Downtown Disney and transfer there to a bus to poly. We left an hour early, and two hours later we showed up at the poly. They did still have a table for us but it was a very long evening. That night after dinner, The nice lady at the Poly front desk called a taxi, $20 and 15 minutes later we were at our resort. We used a taxi once more on that trip for an ADR and it was worth it.