it seems to be agreed there were no kids living nearby. Whatever the risks to wildlife, nothing happened to any of it. But he didn't think of the neighbours' cats. That's regrettable but I don't think it's a hanging offence.
On a public right of way would be dangerous. "Near" a public right of way just means "on his own land". I'm inclined to think you should be able to do pretty much what you like with your own land, including trying to kill rats, even if - like this guy - you're clearly living in the wrong sort of place.