Why should he have to?
Isn't the point to win the war?
How can you win the war, if you keep switching sides?
Why should he have to switch sides, if his squad isn't on the other side?
To me, the simplest solution to this whole damn thing, is simple. If the conutry your trying to switch to has numbers, you can't switch. Simple, easy. You stay on the country you want to fly for. You get to fly the planes you want. And you can't just switch sides to be on the winning team and thus throw all the numbers outta wack.