Meatshields are what R.I.M. are. Prime picked up just so they could save themselves and build up their accounts while we noble through them. So no air, prime will use rim as the shield while WE noble through them.
Most RIM players are inside K's totally controlled by Prime and if any are on the border with you just dont attack them and attack a Prime player first. You say we use them as a shield but you could easily chose to instead attack a Prime Player.
It is a simple matter to noble a village close to the Front you want to fight on so if you want to attack Prime then go ahead. i haven't bothered to check your stats but i am guessing you have still not nobled any villages from Prime.
I could noble many of the village surounding me that belong that belong to sad little tribes and then say they were being used as Meat Sheilds but insted i choose to noble into other K's that contain FEAR villages controlled by the players i want to attack. Actually after looking at your stats it seems you constantly noble only Barbs...are they being used as Meat Sheilds by Sparta or Prime? lol
You wouldn't be able to noble Prime villages if you were next door as there would be too many Barbs nearby being used as Meat Shields.