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: Dennis Andrew Nilsen was a British serial killer and necrophiliac, also known as the Muswell Hill Murderer and the Kindly Killer, who murdered at least 12 young men in a series of killings committed between 1978 and 1983 in London, England.