And here are those terms:

"Our first priority is your complete satisfaction with your Eastern Mountain Sports purchase. If you are dissatisfied for any reason and have your original store receipt or web invoice, we will exchange or repair the item in question or provide a full refund."

It's clear that the policy is take care of customers that are dissatisfied with a product, without having to prove or debate the cause of the dissatisfaction.

It's obviously not intended for people to use a product for a year and decide they want something more aero, and lighter, and return a perfectly good helmet.

Reducing this to the absurd, can you buy one of their bikes, with the intent to use it in your goal race of the year, and then return it, never having intended to keep it?

Or can you buy a bike with Dura Ace 9790, ride it 10,000 miles, and then return it when the next generation of Dura Ace is released?

Both are allowable by their policy, but there's also an implicit belief in that policy that the majority of their customers have some moral compass, and will deal with them in good faith.