Loryen
Problem being, if you make neutral a civ, then it's no longer neutral, but rather the 5th civ. And "neutral" then becomes "not a member of any of the 5 civs". If you then make *that* neutral a civ, then that's just the 6th civ, and "neutral" then becomes... well, you get the idea ;) we would need additional neutral civ(s) which decry the 4 civs