I grew up on a livestock farm. We lost hundreds of animals to coyotes. That being said I am strongly opposed to this method of "control" for a several reasons.
When they are set on public land they are in effect indiscriminate booby traps that can injure people as happened in this case. Unless the area is restricted for some reason these men had a perfect right to be there. Public land is not owned by the government. We do expect the government to establish and enforce reasonable regulations to prevent environmental destruction but it is public land that no one owns. If it is within the boundries of this country then citizens of this country have a right to enjoy nondestructive travel, camping, hunting and recreational activity on it.
I am a hunting dog (hound) enthusiast. Hunting dogs are expensive valuable animals that thoroughly enjoy their "occupation". Hunting game animals with dogs is a commendable legitimate activity. Hunting preditory animals including coyotes with hunting dogs is an effective way to help control their populations. Hunting dogs and other pets are likely to be killed by these booby traps. If an area is seeded with them then that prevents hunting with dogs.
I shot a few coyotes but I also used Pyrenees dogs to protect my livestock. I found that three or four Pyrenees working together are very effective. Pyernees instinctively assume ownership and the role of protector of a flock or herd. (If they don't have a flock they assume those same roles with their human family.) They prefer to stay with the flock and sleep with them at night. They can and will catch and kill coyotes that try to intrude. They have no fear of any bear, lion or wolf and will fight to the death. As an aside, it is a bad mistake to physically assault a member of the human family of a Pyrenees if the dog is present.
I do not believe that using indiscriminate, poisionous booby traps to try to kill coyotes is desirable or necessary.