'Engagement' is overrated. Some sites , e.g Google and Wikipedia probably have super high bounce rates, because they solve your problem on the first page you see. What if people start entering his site mainly from band pages, get all the necessary info and leave? That wouldn't be a bad thing for users.
Actually, that would be a bad thing for his site. If he gets one-time visitors, he will need to keep growing to offset the churn rate. That means he'll probably need to rely a lot on search engine traffic, and for the viral growth to continue. If both go away, his site is dead.
