radu,
you are right about the history of the term moro (Philippine history books and online information will bear this out).
i guess the person you were talking to was non-moro, never lived in mindanao and didn't take his history lessons seriously.
if your friend cares to know more about the moros ask him to visit
www.bangsamoro.com. The following definition are from that site:
Moro.
n. - a citizen of moroland;
Bangsamoro.
n. - a proud race of proud moros.