The article also incorrectly claims that curve25519-dalek has never had security audits. It's had at least two by reputable cryptography auditing firms (Quarkslab and NCC), the former of which is public (the NCC audit was done at the request of my former employer and is private, but like the Quarkslab audit only found minor issues):
https://blog.quarkslab.com/security-audit-of-dalek-libraries...