"fear of being persecuted for... nationality, membership of a particular social group, or political opinion"
Fear of persecution has absolutely nothing to do with leaving a dead tribe to join another.
Take it to the realm of sports. You are a good player, you've had a pretty good career, but you're team recently started falling apart. You get an offer from another team that wants you, and they are in a much better situation than your current one, do you stay or leave?
A true refugee is a civilian, in the context of the UN. These are people that cannot protect themselves, so they find solace in another place. The things you are talking about are more like if France got its butt kicked by Germany, so some of France's military that is still wanting to fight joins up with Britain's army so they can more efficiently work. That is a much more accurate example of what happens than saying refugee. Its a term people have come up with in this game that doesn't really fit (like nuke).
edit: and yes rich, that is a large part of why I go on the externals.