There are no proprietary technologies in Gentoo, it is all open source. Even if there were, Danial Robbins would not be able to sell them as he would no longer own them.
The guy created a great distro and community, but in doing so ran up five figure debts. Now he needs a job and Microsoft offered him one. In a way, Microsoft are retroactively funding the creation and development of Gentoo, without gaining any advantage from it
"Insanity: doing the same thing over and over again and expecting different results." (Albert Einstein)