Its basically just not allowed. But its also a way for players to cheat. As stated in the past new players earn upto 500 rubies when they start the game doing the tutorial. Going on that for the moment. If a player creates 100 alts they could transfer 50k rubies to themselves. This is one of the reasons rubies can't be transferd between players. 100 alts is probably an exaggeration but basically the theory stands run out of rubies create an alt or so. 

If they need rubies, I suggest showing them how to get them from the game by in game tournaments without going crazy. Being new he can get higher on the boards for his league than compared to where you and I would be. 

 Its been said in previous posts but you can go thru this game becoming a heavy hitter player without ever spending a dime. But I do admit having rubies is nice.