I don't know what the acoustics would sound like for a musical performance at the AA stage, but that might be the most logical place to hold such an event(s). Like you said, placing a live band at the Hollywood Bowl stage could create traffic flow nightmares with the SS queues as well as all along the "Plaza of the Stars" road. If this rumor ends up being true, it will be interesting to see how Uni handles the potential problems associated with the setup.
IMO, if they are looking at bringing in another show, I'd much rather see an "arrival" type show that is specifically HHN themed.