Now, I don't think the PRs with the Forgejo folks show a lot of warm collaborative energy on their side, either, but I can see how soft skills from the author would likely have taken their PRs a lot further in getting what they want.
But the author's whole attitude is that Forejo is such a mess and it's barely worth their time to try and clean it up. Nobody's twisting their arm to contribute to an open source project that they don't even like!
From the perspective of Forgejo maintainers, the author is just some random new contributor barging in and telling them to drop some legacy support that hasn't been discussed in detail yet. And of course, this new contributor hasn't actually followed the security policy to disclose it as a high severity issue to justify the change.