Not only is this article three years old, it is also lacking in terms of sources. Additionally, the language and phrasing is quite inappropriate for the purpose of spreading the information. Lots of text is just mean and offensive without any actual purpose.
It also seems to be largely based on speculation rather than actual solid evidence.
I'm not against investigating the legitimacy of established and trusted privacy-first providers. However, this seems a bit lackluster.
Also: Email is inherently insecure, we all know that. Proton services are open source, independently audited and verifiably E2EE, except for Mail, which uses PGP for the emails themselves and E2EE to store them.