You're absolutely right that it can't be said with certainty that the parents are at fault. It could be that the child has shown no signs of a learning disability and so the parent sees no purpose in it. Maybe they've noticed other things which lead them to believe their child has changed for the worse due to outside influence in the form of good-for-nothing friends or media (such as rap music). I don't know how possible any of these scenarios are, but they are certainly plausible on some level or another, and I suppose I could ignore the fact that the parent should be controlling what media their child does and does not consume anyway just as they should be keeping an eye on what sort of children he or she associates with.
I just think you have to ignore an awful lot to not see the parents' actions responsible for how their child potentially behaves, especially considering what we know of the parents in this situation. That isn't to say that I think this kid's parents are bad people, just in over their head. I question how well two working parents can provide for six children. They may be doing their best to be good parents and still failing for reasons that aren't necessarily their fault. I just think it's absurd to blame the child or call him "lazy" from the limited facts that are available.
If he's received an F in PE then he's fundamentally failing to follow instructions given by an authority figure, therefore it seems unlikely that his behavior can be attributed to a learning disorder unless he's so severely handicapped that he can't even do as his PE teacher says. This sort of behavior doesn't crop up over night, and it's extremely depressing to see his parents resorting to ineffective, damaging tactics when there's a good chance that he's behaving this way as a result of how he was raised.
It reminds me of parents that argue corporal punishment should be allowed in the home despite the fact that there is a scientific consensus on the subject that it is damaging. Often they'll make the argument that it's necessary to deal with children in particular instances, yet they can never quite qualify how they know it is the only solution to the problem. Furthermore they never seem to wonder if the fact that they feel they have to hit their children (whether it's a open-palmed strike on the ass is still hitting) isn't a symptom of damage that's already happened to the parent-child relationship.
This is no different. There's no good reason why a parent should have to resort to these levels to keep their child under control. The fact that they engaged in this should really send off alarm bells and make you wonder what else they do. There's a reason social services is looking into this. They know, from experience and careful study of statistics, that when parents act like this, there are often deeper problems that they haven't even scratched the surface of.
Returning to an earlier point, let me pose a question. It has been suggested that the child's parent should have an easier time resolving problems with the child because they know them and have an emotional connection with that child. This seems plausible at first, but in what problem-solving scenario does the presence of emotion actually make the situation easier to understand? I can't think of any. Emotions make things harder to grasp, not simpler. We often can't see things because we're too close to them. No parent wants to think that they are in part responsible for their child's behavior. That's often why parents go to such extreme measures in disciplining unruly children: because they feel responsible for their child's misbehavior on an unacknowledged level and are seeking to wash away that embarrassment and disappointment (part of which is directed inward) with a vindictive response.
I think every parent makes little mistakes like these in some way or another, it's unavoidable. Thankfully, human beings are pretty resilient so a few mistakes here and there typically don't add up to a delinquent. The problem is, there are a lot of overly punitive, damaging practices that are condoned in America today. People applaud these stern approaches to discipline from a perspective couched wholly in pop-psychology. We're convinced that things like "tough love" work based on flawed anecdotal evidence and experiences that are just riddled with confirmation bias.
If we're serious about progressing our society we have to be serious about making progress in all things. Part of that is perfecting the processes by which we raise our children. I can't think of a way to do this that's better than analyzing, critiquing, and eventually changing our cultural notions on child rearing through utilization of the soft sciences. Doing nothing certainly isn't going to make things better, so either we listen to qualified experts, go out on a limb hovering over the abyss of insanity with James Dobson, or do absolutely nothing in the name of preserving traditional ideas which we empirically know to be invalid yet somehow place faith in.
There seems to be an outpouring of sympathy towards the parents of delinquent children in damn near every situation, never once considering that children are shaped by their parents more than anything else in the vast number of circumstances.