Protector is a lame name. It sounds like a car security system. Even if he isn't "the" Captain Marvel it makes more sense that he would keep the name since it seems more in line with what Bendis is trying to do with The Avengers. We've got Captain America, Iron Man, Thor, Spider-Man, Wolverine, (a) Hulk, Spider-Woman, Hawkeye and....Protector? WTF.
Anyway like I initially asked was there ever a reason given for him not assuming that name permanently?