hmm good question. Years ago this seemed to be an important topic, but it seems to have faded away to the fringes. I do not know if that is because it just never caught on or was widely accepted or supported by all Browsers or if there are problems with it or some other reasons I can think of. The CSP documentation was published in 2012: http://www.w3.org/TR/2012/CR-CSP-20121115/ There seemed to be some usage for about a year and then it just faded away into obscurity. Not really sure why?
In any case, the link you posted is for a tutorial in 2012 and the site is not a WordPress website. Just looking at the basics of what and how CSP does what it does I believe it will break WordPress and is not usable on a WordPress website. That may be the primary reason it faded away into obscurity since WordPress websites are now somewhere around 24% of the website types used Worldwide.