The author mentions installing Ghostery, which appears to be nonfree.

It is free, unless you have some politically overloaded definition of free.

Please don't be so simple minded. I mean that for your own sake. The English word 'free' has more than one common meaning.

I think the definition here was Free Software, which considering it doesn't seem to have a public repository with the source code, means that it is nonfree.

Just in case that's not clear, when people capitalise "Free Software", they're generally referring to the definition used by the Free Software Foundation.

Nice catch! Straight-up error on my part.