All the more so because current "jruby-on-Android" has performance problems. This hits particularly hard on startup (where a simple app can take several seconds to get past a splash page; see http://ruboto-startup.heroku.com/measurements for timing). But even once the app gets running, things still drag compared to a conventional JVM because the JIT doesn't work (due to Android's nonstandard Dalvik bytecodes).
If rubyflux winds up bypassing most of this overhead, it could be a major win. (Right now, I've got a project to try to use Scala to try to build a full-featured, reduced-boilerplate Android environment here: http://rst.github.com/positronic_docs.html --- but I'd really rather be using Ruby if the performance penalties could be ironed out.)
I bet it's mostly for fun. He essentially extracted his JRuby JIT into a conventional compiler.
In other words, a neat hack.