You seem to have hallucinated that I said that swift cannot be made to run on other systems. You can even make windows-only games run on linux so that is not a surprise.
What distinguishes swift from gcc, clang, python, bash, go, rust, and so on is that languages other that swift aim to support linux in general.
"and so on is that languages other that swift aim to support linux in general." -> again not true linux distro dosen't change swift usage it is just official build is run for few most popular distros and you can use prebuild swift-bin on any linux repo. (arch, debina, ubuntu, centos etc. etc.) You can say the same stuff about rust/nim/go every other language that didn't have official release for some niche linux distro.
Swift here are basically saying they'll endeavour to make sure it works on those particular distros, but in general you're probably going to install Swift on Linux the same way you install rust; via your distro's package manager, and supported by your distro, not the Swift or Rust project.