How do you know that? Perhaps "Dad" wasn't "Dad" at all - but stepdad and the kid had been (and was continuing to be) victimized by a contentious divorce? Perhaps the kid did have sensory issues. My daughter goes to school with two little girls, both with an entire suite of 'issues' and both with parents who seem - problematic. In one case Mom left when she was four, showed up again when she was five, rehab involved. Mom comes and goes, alternately spoiling her and ignoring her - and Dad is more interested in his girlfriend. That one you CAN - to some extent, blame poor parenting, but since there is also mental illness involved, its more complicated than that. In the other case the little girl's brother died of cancer last year - after a five year long struggle - and the whole family is a dysfuctional mess - with some good reasons.
I'm always amazed at the ability of Disers to be able to be exposed to a family for fifteen minutes in line and be able to be able to identify exactly what has gone wrong within the family unit accurately. We seem to know when its poor parenting and not autism or sensory disorder. We seem to know when a kid is a brat and not that a perfectly normal kid just didn't reach his limit for the day without warning. We apparently are all in the wrong profession, since we'd all make such efficient social workers, school psychologists and family therapists.