As far as the Nationality issues are concerned, it appears that the Aurora Borealis is not the only untracked glacier in Iceland. There are the Enerjikkla, the Eynja and the Hveragerdi as well. These three glaciers have all been trekked by tourists in the past but with little or no success. In fact I have personally done several day tours of all three glaciers and each one of them was reputed to be a challenging day hike in the standards of high altitude mountaineering.
With regard to the Aurora Borealis, and the Nationality issue, it appears that it may be difficult for an out of country skier to access. The only means to access this region is via the Aurora Arktika ski resort, which is located at the base of the mountain. It appears that the authorities in Iceland may want to restrict the number of visitors who can access the arktika and in fact has made a number of specifications as well. These specifications however are not clearly defined and thus it is possible that anyone who has the necessary qualifications to access the aspen lift access backcountry skiing trails could easily get a permit to skiing the arktika and so become a guest of the national glacier.
On the other hand, there appears to be no problem with out of country skiers accessing the Aurora Arktika. There are many ski patrols operating in this region. If you contact the tourism office in the area you will find out that all you need to do to access the ski slopes is fill out a short application form. You will also need to provide some basic information about yourself. You will be required to state where you live and how long you have been living in the area. Once you have submitted your application you will receive a temporary visitor’s visa and be on your way to enjoying the great outdoors of Iceland!