I used the word 'posse' I believe - and by that I mean the first definition as indicated in
this link. - a group of people encouraged to assist in law enforcement. Edited to add the fourth definition could also apply "A group of friends or associates."
He is acting as his own sheriff in this case, not wanting to go traditional routes to see a crime through, and his fans and other folks who object to the actions of the book pirate are also supporting him.
Nothing wrong with it, as long as he thinks that is a good enough solution to his problem.