I'd start by checking saddle height. It could be too high causing him to rock left-right with each pedal stroke and irritating sensitive parts. Or it might need to be set back a little more. A great deal depends on the saddle shape and how he sits on it. It might be that he only needs to find the right saddle position for that saddle to be comfortable.
So if your mate hasn't done so already then I'd certainly suggest he experiments with saddle positioning before buying a new saddle. It's an expensive game if you just start buying saddles hoping they'll fix the problem.
If there's no joy in any position then have him consider saddle shape. Obviously saddles vary; in flatness or roundedness, width varies at the rear and the nose. It might be that he'll get on better with a flatter saddle that has a narrower nose. Or maybe not. Sadly, there is a degree of trial and error but if you think about it first, the better your chances of buying the right saddle. Think about where the irritation is occurring and visualise what you'd have to change about your current saddle to reduce that irritation - then look for a saddle that matches that mental picture.