Would you enjoy it if the UFO spawned a lot, and had multiple UFOs flying around, making PoE2 a sci-fi flight simulator? Or would you rather the UFO be rare so as not to affect gameplay and stay an easter egg? Why not just try it and alt-tab out of BF2/PoE2 to let it run while you browse the internet for 30 minutes?
Also, earlier I posted the level's vehicle spawning information. Go into PoE2's levels and view the GamePlayObjects.con and see for yourself.