I'm unsure on who is better placed to handle that stuff now. My view is that the people that were doing that are now with gem.coop, but rubygems still has the infra (i.e. you'd email security@rubygems.org still for now).
I'm unsure about what to think about longer term (my personal approach is currently "wait and see").
Similarly, I'm perfectly happy with bundler for now, but if `rv` turns out to be like `uv`, I'd happily switch (drop-in replacement, but faster/some better features).
[0] https://www.bleepingcomputer.com/news/security/60-malicious-...
[1] https://blog.rubygems.org/2025/08/08/malicious-gems-removal....