You can run at a FC of 1 with a SWG, a low CYA level, borates, and some very careful level balancing. Moss is not required. Plus it will have essentially all of the advantages they claim. Remember, they only say not to go below a FC of 1, they don't actually promise that you can get that low. Getting FC down to 1 is pushing it, but an FC level of 2 is not really all that difficult with an SWG and borates and a suitable CYA level.
Even if the moss has the properties they claim, I can't imagine that a few cups of moss will do much for an entire pool for a entire month. If they were filling an entire 300 lb sand filter with moss I would be more inclined to believe it.
Regardless, someone is being very clever about the marketing.