Hi Daniel,
Thank you for explaining this and creating issue. I think that should be supported. Whoever develop custom addons for mobile application, most likely would need to develop his own services to support it. I personally hate idea to hack moodle core code or plugins that are not mine and add services there. I might live with at the moment since I'm still in development phase, but once I'm close to the delivery, I would be very happy to have this feature.
Thanks,
Zoran