Bus transfer from Al Ain is extremely problematic, and probably wouldn't be attempted unless the aircraft were dead. The first issue to resolve is that of the local authorities. In many cases, depending upon where you've come from, they will not allow you to disembark your passengers at all, and going landside would be even more difficult. Beyond that, most of the passengers would have been intending to remain on the aircraft out of Dubai, so getting to Dubai without the aircraft means that either it, or they, would have to wait in Dubai anyway. Unloading the cargo from a 380 in Al Ain would also fall into the unlikely category. You'd have trouble organising it will a couple of days notice. A smaller aircraft...much easier.
The intend was never to stay there for any length of time. Sadly ATC's slot management there can totally stop the show. It's a Cat III airport, but only in name.
Off-line airports are always shockers...and the only reason you ever go there is because the aircraft won't keep flying indefinitely.