Probably will be fine but without knowing the draw from everything he is using and knowing what the stator is putting out that is wasted, it is impossible to know or give a proper answer.
What I would say though is if he bought a battery indicator that he could keep an eye on such as this
He would know if he was using to much power at any given time and could switch something off that was not really needed. Simply putting a tester on at tickover wouldn't really give a full answer because of the following. Suzuki use a 3 stage charge system, so is putting out more or less power depending on how high or possibly low the revs are (I think) which in turn would mean that although you may be running the battery down with everything running at tickover but when riding quickly or within a higher rev range the stator will be kicking out more power.
Sorry I couldn't be more help Crash but I ain't got the time nor inclination to do a load of research on possible electrical issues on a bike I don't ride. Hope what I have written does help a little though