Linux is not in the public domain. Linux is a cancer that attaches itself in an intellectual property sense to everything it touches. That's the way that the license works.
Bio: Julian Philip Matthew Johnson was an American surgeon and author of several books on Eastern spirituality. He spent much of the 1930s in India, was associated with the Radha Soami Satsang Beas movement and Surat Shabd Yoga, and wrote five books as a result of his experiences.