Mark has made it pretty clear that he's pretty much ashamed of Creed and it's music. I remember the comment he made about WAWO, and how people shouldn't remember them for that one song. Funny thing is...when I hear that song, Mark doesn't come to mind.
If Alter Bridge wants to perform Creed songs, I guess they could. I don't really see anyone stopping them from doing it. It would be hard though...because Myle's voice just doesn't fit. Maybe that's why they haven't.