Would it be possible to add a tag to player ID's that have switched sides recently to avoid gameyness?  player switches sides to "pre-emtively level a friendly town for squaddies", attempts to bomb friendly town but cannot because of  switched sides flag. Furthermore, he kill-shoots himself by bombing town buildings due to this flag. 
It will always be a battle to figure out how to take advantage of the rules of the game (within their confines), but i agree that carpet bombing your own town shouldn't be such a readily available option. 
Bomb-t*rding at they say shouldn't be without penalty within your own town.  Not an easy one, but a valid wish from legitimate complaint IMO