The numbers of results there vary wildly upon refreshing the page repeatedly. I'm getting ranges of 39k-79k for Go, 12k-42k for Swift, and 3k-9k for Rust. Also, in the absence of knowledge of what precisely is being measured (e.g. does it include forks?), we should probably only interpret these numbers as order-of-magnitude comparisons.

Swift repos will pass Go within 12 months. I think most iOS developers were holding off on Swift. Heck, Xcode and Swift, etc only became usable earlier this year.

Most people aren't writing open source iOS apps.

No but there are a lot of components.

I think that doesn't support your hypothesis--- 31k in one year compared to 70k in 6 years implies a lot more momentum for swift than go.