alt Hacker NewsA language is more than a compiler. All of the Swift frameworks you would need to do anything actually useful or interesting in the language are macOS-only. You cannot develop in Swift for Windows/Linux/Android the way that you develop in Swift for macOS/iOS. That matters.
You don't need to convince me that Swift is poorly positioned there, but if you only care about server side (or possibly CLI) apps, the usable ecosystem on Linux isn't too shabby.
Does it make sense compared to C#, Go, Rust or a JVM language? I don't know, but it's there, and Apple put some resources behind the initiative.