It doesn't matter how you arrive AT MCO....you can arrive by bus, car, plane or yak. You get to ride the DME bus to your resort, as long as you made your reservation for it. You can tag your checked bag with the yellow tag if arriving by plane, otherwise leave it off. That tag calls attention to your bag as soon as it comes off the plane and baggage handlers will take it and put it aside for DME transfer, by truck, to the resort. I've seen many people, standing in the DME bus line, attaching the yellow tags..no need. The bag is nowhere close to those that need to see the yellow tag!
Where a lot of people get confused is being able to use RAC (not DME) when returning home. RAC (Resort Airline Checkin) works with specific airlines. Southwest was one of the last to join the group that can use RAC. This is where you would go to check your bags in, and get your boarding pass. You can then return to MCO on the DME bus, in your rental car, or via a car service..doesn't matter.
So..long story short? Anyone can use DME to and from the airport..airline doesn't matter.