I would think the only requirements for being a greeter is that you know a fair amount about the game, i like to think i am fairly experienced in at least the low level aspects of the game and i would be quite keen to help some of the new people, i promise i wouldnt twist them into worshiping me as a cult idol
also, i think it can be quite difficult becoming a strong f2p such as training all the alts and stuff, when going p2p there doesnt seem too much difficulty leveling to at least level 100, just pwn ai with drones, though i do think that people shouldnt complain about the small difficulties of training f2p chars, you dont pay so you shouldnt get an easy ride, though since i am f2p i cant really comment..
anyway, i think that more greeters would be a fine idea and who better to help new f2p's than the people who know the most about that part of the game, the pre-existing f2p's?