There's an easy explanation. If you look close at the crowd to the mayor's left you can see David Pepper, the mayor's opponent in their last election. He was aiming at Pepper, but hit the umpire in the belly instead.
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 .