Possibly panic? We don't know?
The other boy said that the victim was looking at him and had his hand out for help, and his reg was out of his mouth. That does not sound like he was dead. But why make an assumption?
That however has not been the general consensus of dive medicine doctors in decades. There are many articles on asthma and diving. The gist of them are that asthma does not necessarily contraindicate diving. The determination of whether someone with asthma is fit to dive is made on a case by case basis and involves, among other things, lung volume, severity and triggers of the asthma, how well controlled it is, etc.
My point is, why are we assuming facts not in evidence? And why are we assigning blame to the victim or his family, especially since the source of that blame has not even been confirmed? Why are we assigning blame at all?