Until that last picture I was going to say he probably doesn't realize he's being watched, so just pointing out to him that he'd been caught would hopefully be enough. The last picture shows he's just some idiot kid.
So, is it on public or private land? I believe MN has some provision about disturbing someone elses bait site, but I don't know much about enforcing it. I would say go through the reg book real good and see what it says. It's possible that if it's public land you're just out of luck.