I agree that Android players should be lumped into the "mobile" classification for sparring, the GST, and other purposes, but I understand why it isn't. It's very easy to use external peripherals on an Android device and also very easy to emulate Android using a PC, and there's very likely no way for Graal to understand if either is happening.
Either way, I don't think Android users are going to be rushing to buy external keyboards just to have this perceived "advantage" in one side of the GST. I feel like they should just let it happen despite those issues, but oh well.