It's Criminally Negligent, and that's only if no-one is hurt; it escalates if someone does. In Canada Criminal Negligence Causing Bodily Harm is a Criminal Code offence carrying a maximum penalty of ten years imprisonment while ~ Causing Death carries a maximum penalty of Life in Prison. And remember, Canada does not give time off for good behaviour, and if paroled, you are always on Parole for the entirety of your remaining sentence.
The local Sheriff in that particular story is negligent of duty; this is a serous criminal act that he is condoning.
With repercussions like that, it's no wonder people do such things in the first place. This is really no different than dropping concrete blocks off of freeway overpasses, and similar antisocial acts. Perhaps someone should send the Sheriff a copy of the Broken Windows doctrine.
If a member here (or elsewhere) advocates it online, he is not only potentially criminally responsible if someone takes him up on the idea, he is also not smart enough to be a successful criminal, as he has left excellent incriminating evidence, so he should perhaps consider keeping his illegal thoughts to himself in future.
And in case someone wants to bring up the "can't happen here" defence, I personally know of a young person who was decapitated by a wire fence gate while snowmobiling, and he was not travelling anywhere near highway speeds; his father was a good friend of mine in High School. Now, in that case, it was a gate on private property, and didn't result in charges being laid. But I guarantee it would have been different strung across a public highway.