I’m definitely not disagreeing with you, but the Linux story isn’t completely horrible mostly due to IBM’s work. Though I’ve no idea if they’ve kept pace with the macOS version and tooling, it’s been a couple years since I looked. A shame, I quite like it as a language.
And even with all that support, it is not possible to write OS independent Swift without kludges (import darwin vs glibc, really?).
Also many enterprises impose Windows desktops, so none of their dev divisions would even consider Tensorflows's Swift variant, regardless how well it would be doing on GNU/Linux.