My question is what would Law Enforcement have accomplished had they responded and arrived before the house blew up? In similar cases of this type, the first thing LE tries to do is establish contact with the person/persons inside the home. Considering the father had planned his murder/suicide prior to the children arriving, I doubt LE would have been able to prevent him from carrying out his plan. The ONLY way to have saved the two boys would have been to deny the father access in the first place.
If the court is going to order supervised visitations for whatever reason, the judge should be smart enough to realize that it should be done in neutral territory that the non-custodial parent does not have any control over as a simple precaution.
That said, it probably would not have prevented this murder-suicide debacle. This murderer would have simply come up with a different plan to attack his children whether at school or the grandparents home.
It appears to me that the killer’s relatives have all been ignoring the elephant in the living room in regards to whatever dirty family secret that drove the killer’s homicidal familial control obsession. For that silence, they bear the burden of contributing to whole sorry tragedy.