Considering we haven't been told much of anything by Square how the Glamour system works on a system-level, I have no doubts and I can make no assertions.
If, it were simple enough to simply toggle the glamour-ability of an item, which it might be, then you could easily not toggle this ability on the AF armors.
Or, as otherwise suggested, they can very clearly change the restricted classes on items from JOB/CLASS to Disciple of War/Magic, to all class. Adding an ever increasing list of same-model armors for certain classes would just contribute to bloat.
