I think the benefits of federation is discoverability. I can spin up my gitea or forgejo (or something else!) Instance, but when people look for code in their instances, they can still discover my public repositories, and if they want to contribute, they can fork and open PRs from their instances.
So yeah, it means mostly you can selfhost and provide space to others, but with the same benefits that right now github offers (I.e., everything is there).
The biggest items on the graph are all out of bounds accesses, use-after-free and overflows. It is undeniable that memory safe languages help reducing vulnerabilities, we know for decades that memory corruption vulnerabilities are both the most common and the most severe in programs written in memory-unsafe languages.
Unsafe rust is also not turning off every safety feature, and it’s much better to have clear highlighted and isolated parts of code that are unsafe, which can be more easily reviewed and tested, compared to everything suffering from those problems.
I don’t think there is debate here, rewriting is a huge effort, but the fact that using C is prone to memory corruption vulnerabilities and memory-safe languages are better from that regard is a fact.