From what I understand about this case, the bowel condition that caused the death of the infants happens occasionally to preemies, but it usually starts earlier while they are still in the hospital. In these two cases, the infants had been released from the hospital and the condition started at home.
I'm guessing that the parents had been told to use SimplyThick for the same reason PALS are told to use it -- to prevent choking on thin liquids (aspiration pneumonia hazard) and SimplyThick got caught up in the Adverse Event Reporting System because the circumstances were unusual.