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: Sir John Vincent "Vince" Cable is a British politician who was the Secretary of State for Business, Innovation and Skills from 2010 to 2015 and the Member of Parliament for Twickenham from 1997 until losing his seat in the 2015 election.