If one team can fly away in a vehicle with the flag then it follows so could the other. Imagine the dogfight battles!
Besides, the game has unreal in the title!
Now, this is not without precedent:
1. Strangelove & RX have flying vehicles:

2. Bat-wings lets players fly with the flag:

3. Even Rosebum's flying saucer can carry the flag:

Given all that, why not XV as well?