Okay, you can pick between 90% NIH with some sharing or 95% NIH because you tried to stop the sharing. The amount doesn't matter; you're still causing more AI use.
And nothing actually prevents a vibecoder to clone a repository on SourceHut, they just would be less able to add a ton of crap to it and spit it back on SourceHut (they'll just spit it back on GitHub).
I guess that's also a plausible possibility. Honestly I mostly don't think sr.ht has enough market share to matter either way.