Doug,
You can tame a ball by shining it to get it through the heads but its going to be very "squirty" on the back end and inconsistent. The other option is to plug the ball and put a weaker pin out drilling pattern in the ball and take any leverage out of the ball if it has any in and put a neutral weak drilling pattern in it for length.
If your friend has the cash, I would go out and get a "tamer" ball. I mean lets face it, he spent probably 200 bucks on a super reactive ball and what you suggest to do is to take that ball and turn it into a cheaper ball. If it were me I would leave it alone and use it on heavier oil patterns or tournaments and go out and buy maybe a BW Pearl or something a little less reactive on the backend but still gives you enough punch and would be much consistent and easier to use as the oil breakdown on the lanes. Thats why I tell everyone who asks me about buying a new ball is do the research. Know the lanes you ball on, know what your release is and what you want the ball to do. Go to the pro shop and check out the various ball review magazines and talk with your driller. After you compare all the options and have the info you can make a decision about what fits best in a new ball. Good luck and hope this helps.
HM, Level I USBC Coach