As far as I can tell it's not necessarily targeted at Android developers. It seems like the primary use case is if you have some device with cell service and you're out of WiFi range but want to use your Android device with an internet connection.
They must have customers that are in that situation somewhat regularly (traveling business people?) and keeping the overhead low is desired.
> At Genymobile, we wanted Gnirehtet not to require the Java Runtime Environment, so the main requirement was to compile the application to a native executable binary.
While it is nice to see new projects adopting Rust, I really don't get the point of having a tool targeted to Android developers not depending on Java.