I think it would be nice if EJ could earn PS, but I understand why it was restricted.
Even with the restrictions though, an EJ player can kill all the spawn mobs just as well as any other player, without any limitations. They won't get the pinks and 105s along the way, and they stand aside when the boss is up. If they are in a sharing sorta guild, their work for the spawn should be worthy enough to roll on the PS that drop from the boss. If an EJ is a PK, they can kill the players that defeated the boss and loot their PS just the same as anyone else. They can steal them, also.