The license is addressed to anyone, but an individual user gets an individual license.
> Furthermore the AGPL is explicitly irrevocable.
The Mastodon authors can not choose to revoke the license, but the license itself contain clauses which specify revocation under certain conditions, and after a certain time delay. This is one of the areas in which the GPLv3 (and AGPLv3) is more lenient than the old GPLv2, which was automatically revoked instantly upon any license violation.
https://www.gnu.org/licenses/agpl-3.0.en.html
Revoke may not be the legally correct word to use, but it's an informal blog post and not a legal document, and what they intended to say is clear enough.
I think that your understanding of how the licensure works is a bit off. Open source software is still individually licensed to everyone. The copyright holder retains copyright, and can terminate an individual's rights under the license as long as the license includes a termination clause. Which the AGPL does.
I did not take termination into account in the second paragraph. I was referring to AGPL being addressed to anyone instead of a specific party. This means that a full revocation of the license would revoke it from everyone, even though that's not possible with AGPL. This does not apply to terminating licensees as you mentioned which appears to be what they mean and is possible under condition.
But because of the lack of a violation a permanent termination in 30 days would still be invalid.
> Many users were able to create accounts and use it
> the AGPLv3 requires that you provide (to every user) an opportunity to receive the entire Corresponding Source for the website based on that code. These early users did not receive that source code
https://sfconservancy.org/blog/2021/oct/21/trump-group-agplv...
AGPL can also not be "permanently revoked". It's not individually licensed to each user like proprietary software often is, it's one license addressed to anyone. Furthermore the AGPL is explicitly irrevocable. They can change the license to a proprietary one but this does not affect existing copies under AGPL.
Last I'd like to touch on "antithetical values". If Mastodon were to discriminate against persons, groups or fields of endeavor in their license they would no longer meet the definition of open source, but rather become a source available proprietary product.