For those who didn't read the article and wondering why you would use svg fonts which are supported only in safari vs the usual technique of woff which is supported everywhere,its because svg allows bypassing csp restrictions if its embedded in same document.

I'm personally kind of surprised that you can have font-src: 'none' in csp, but still allow specifying an svg font as #foo to load from same document without violating csp. I kind of thought you'd need 'self' or something. data: is already banned by this type of policy.