Plantar fasciitis is a multifactorial problem that is not always a "running injury"—a lot of people in the general population get plantar fasciitis too, so in some cases, runners who have PF maybe would have gotten it anyways even if they didn't run. The same can't be said for a lot of other running injuries. Most treatments for PF are judged simply by how much they help—there's no slam-dunk super-effective treatment as of yet, since there are so many factors associated with it. If someone wears hard-soled shoes and is on his feet twelve hours a day, an exercise can only do so much for him—he's putting a ton of stress on his feet.
That being said, it's great that there is new research into using strengthening exercises as a way to promote healing in plantar fasciitis. In many ways, PF is quite similar to Achilles tendonitis (really tendonosis, and fasciitis is really fasciosis...): it's a degenerative overuse injury of a thick band of collagen in the foot. Heck, in young people, the Achilles tendon and plantar fascia essentially run together. The major difference is that there is a heavy-load eccentric exercise for Achilles tendonitis—Alfredson's eccentric heel drop protocol—that has demonstrated very good results in treating Achilles tendonitis, most likely by selectively remodeling the damaged and degenerated areas of collagen in the tendon.
No such exercise exists for plantar fasciitis, possibly until now. This study appears to be the first that investigated an eccentric exercise for treating PF. Rasmus Oestergaard Nielsen, the lead author in this study, has put out a lot of great research in the last several years, so this isn't just some crank professor with a wacky idea.
I will be reading this study as soon as I can find time and I'll post my thoughts.