I agree that Neil Finn is the band leader and chief decision maker, although I'm saddened by this. I hope Mark knew of his exclusion at the time of the gig announcement. If he didn't, that would be pretty ordinary.
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .