With the landing gear down? That would have been one rough ride! Furthermore, the drag caused by the gear would probably have eaten up their fuel at a very considerable rate. I doubt if the plane could have made the flight due to excessive fuel consumption. (just guessing here, but I think that it's a pretty good guess).
The A320 Airbus, that was involved in the incident yesterday, did not have the ability to dump fuel, it was built that way. I don't know if that is the way all A320's are built, but it might be. And I think there may be several Airbus A3XX models that can't dump fuel.
It might be that Airbus Aircraft are flown allot over Europe, and there is no place to dump fuel in an emergency, or EU environmental regulations forbid it. Where if an something over the US near the coastline, the airline as the ability to dump fuel in the ocean. That is why yesterday, the plane had to fly around for several hours to burn off fuel.It would be interesting to see how if the same feature is employed in the A380 (500+ passenger) planes. How long will the plane have to circle to burn off the excess fuel, before it could safely land.