None of the tools described in the article are open-source. Call me paranoid, but that doesn't pass my bar, both from a security pov and from a long-term recover-ability pov.
Veracrypt [0] is open source and has passed a security audit in the past (when it was forked from (Truecrypt). I use it for encrypted volumes and it has extra features for the truly “paranoid”. Combine this with Backblaze and you’ve got yourself a good secure backup for sensitive/personal data.
[0] https://www.veracrypt.fr/code/