From the article:
For himself, anyway. I'm assuming that Kolb, who was inspired by the song's strong storyline and imagery, didn't want to go through the hassle of getting the rights to the lyrics and so he isn't selling copies.
The book is, however, freely available for download on Kolb's website.
Devin Faraci does raise an interesting point that I find myself agreeing with:
It's interesting that Kolb's vision of the song is very different from mine. I've always seen Space Oddity as not a tragedy or the tale of a space accident but rather of an astronaut who, once he gets far beyond the Earth, has a shift in consciousness.