If you're using eclipse or android studio there's just a single button that compiles and sends your app to the plugged in device, and uses your IDEs debugger, and a logcat window for the system log. There's also an emulator which you could use instead, which comes with the sdk.
So to run a smoke test using a language that's already installed on the computer Tim Bray is using, instead of just typing something easy into a terminal, he needs to download an entirely new application, set that up with his project (which isn't exactly a walk in the park), plug in his device, and then run it?
He wants to run a smoke test on a library he's writing. He doesn't want to run a full-blown application just to test his library, or to have to plug in a device to test his library. He wants to open up a terminal, type "java test KeybaseLib" (or something like that) and have it just work.
