I have not worn a football helmet for 20 years, but what I interpreted from the article was that the players each go through specific fitting process for one helmet that is adjusted with specific staff assistance. The NCAA concern with multiple helmets would be whether they would go through that same process with 5 helmets per player.

Then, it was indicated that a special design process could further form fit the helmet to an individual's head if it provided a lot more protection. If that process cost $100 per helmet per player, and schools didn't pay that extra money for the additional helmets beyond the first ones (because of that additional cost) then they would not be protecting the players properly- because of the extra cost for helmets that the players wouldn't necessarily need- other than for fashion purposes.