Does Pitchfork Media have the right to restrict photography in a public park?

Chicago Reader
The music website has a no “professional cameras, no detachable lenses” rule at its festivals, but Ben Joravsky and Sam Adams note there’s a sign at the entrance gate warning concertgoers that “by entering here, you consent to the use of your image in filmed reproductions of this event.” Joravsky and Adams write: “In other words: we can make money off pictures of you, but you can’t take pictures of us with a decent camera.”