I've been using https://github.com/sekey/sekey for years now! It handles gpg as well

It doesn't look like the author knows what Bitcoin is... They state that "Bitcoin transactions usually cost 1-2%" (sic) which is factually incorrect.

I do believe that "there aren't many uses" for blockchains, but this sound more like an inaccurate, unoriginal and badly researched opinion piece.