Being listed in the AUTHORS file does not imply active participation. libsodium is based on NaCl's algorithms and code, both of which are publicly reusable, but I think they were placed in libsodium by other people. If you clone the repo, `git log --author=bernstein` and `git log --author=djb` return no results.

It's probably worth treating NaCl as something like research code or a reference implementation. It's certainly way more usable than most research code is, which is extremely commendable, but it's still not quite libsodium in terms of its goal as a product.