Well Swift for Tensorflow is more than just a binding to begin with. The difference in maintenance is that Google officially supports Swift whereas Microsoft would be always catching up to keep theirs updated.
> So any language that can target .NET is also able to plug into it, and I certainly would pick F# over Swift.
I can use both Swift for my iOS app (inferencing), training is also possible thanks to Python interoperability (@dynamicCallable), soon to be replaced by native C++ interoperability.
If I chose F#, as much as you may think it is a good choice unless your stack/team is using Microsoft technologies, I see this as a potential sunken cost here and I certainly wouldn't use it for this case and would rather rely on the active maintenance of the Swift/Tensorflow team at Google to improve this rather than using another great language for an unsupported use case.
Even your examples are a proof of that.
Zero persons from Swift/Tensorflow team at Google are working on improving Linux/Windows support.
Linux was been mostly volunteer and some IBM contributions.
Windows are just volunteers, and have restarted the port multiple times.
So any language that can target .NET is also able to plug into it, and I certainly would pick F# over Swift.