What Grant is doing for a living is no different from any other former Olympian's professional pursuits (post-competition). Whether it's sales, retail, coaching, writing, speaking, announcing, etc., they love the sport and their position is one where they can build successful careers within the industry.
It seems, too, that the "Good Form Running" approach, while certainly not entirely original, is packaged in a way that makes things easy to understand for beginners. There's no book to read, no drills to practice day-in and day-out, no physiological mumbo-jumbo...it's all very simplistic. Furthermore, there's nothing that suggests what type of footwear to use while practicing good form...it just so happens that he is wearing a minimalistc shoe in the promo clip.
Grant's a great guy...very humble, very personable, and very altruistic...I strongly doubt this is a venture he is undertaking to get rich at the expense of the 25 minute 5ker. And if he does? So be it.
Best of luck to Grant with Good Form Running...I am sure he will be as successful as other former Olympians have been in their career undertakings.