Well, there's many balls out there a lot more even and calm reacting than the Soul Pearl (I think it's called Soulmate) before going to a what is probably a very early rolling dull old urethane.
Depending on how much oil you are are bowling on, there are balls like
the Storm Tropical Breeze Hybrid, The Storm Ride, Lane Master Wasp and Tiger Wasp are all light to medium-light oil balls that roll fairly evenly. The Soulmate is a very flippy pearl by comparison. Roto-Grip Loco Solid is a polished mild solid that handles medium-light oil but is very controllable. The Arson Low Flare Pearl is also a very good control ball with urethane like reaction,
If he needs a stronger ball, many can be sanded to make them handle more oil and make them even more even reacting. There are many more older balls easily available on EBay that are even more even reacting.
If his speed is that slow,he probably needs a ball designed to handle medium-light oil to enable him to handle medium oil. He needs weaker balls to handle more oil.
FYI Most of the balls marketed today as urethane, except for the new Black Hammer, are really resin/urethane blends meant and designed to act more like urethane. I doubt if he needs or wants such a ball, but being rev dominant myself, I can strongly suggest the current new Blue Hammer; it rolls like a true urethane but has resin like hitting power. It is meant for light oil.
By the way, did anyone watch him bowl before "forcing" him to buy such a ball?? No shop in their right mind watching an old rev dominant, slow speed bowler, like you say he is, would recommend such a ball, if I interpret what you've said correctly..