I don't see any reason why would we implement that command. That would cause problems between players, like national intolerance and would be followed by hard flaming.
At the moment, you've right to kick whoever you wish from Lobby if you are the owner. So it's not really hard to type "!f" and check player's country and kick them if they don't fit with you.
Anyway, i'm glad that you've posted suggestion to us. I'm looking forward to see new suggestions aswell.
Best regards,
Angel