i only use about a half dozen strains, 2 most frequently (001/830). if he was really looking to focus on always keeping strains on hand to keep customers happy, i'd cull your list to the following :
*not necessarily same strain...
i think those are the most commonly used strains and if he kept them in house and monitored his inventory to always keep them in stock, he'd keep the masses happy. prob need to add at least 2 belgians to the list, but i don't brew them often and couldn't tell you which ones to go for.
I'd order in some other strains like Denny's 50, Irish Ale, Alt, Oktoberfest Blend, scottish ale etc on occasion or special order - maybe to fill out a minimum order and see how they sell and perhaps adjust the list as he becomes more familiar with local demand.