Well he does go into Pythagorean tuning later in the video[1], both a proper one and one which was made to "look nice", so bit more to it than that from what I understood.

Or I might be wrong, I know nothing about music[2].

[1]: https://www.youtube.com/watch?v=ghUs-84NAAU&t=517s

[2]: https://www.youtube.com/watch?v=s6EaoPMANQM