On July 8th, 2018, my former family member (former due to a divorce), who is a petite female in her 40s, bludgeoned her mother and grandmother to death with a nightstick. I've known the mother and grandmother since the mother was a teenager and I know the murderess since her birth. Beyond the shock and grief, we all were trying to absorb how ONE small woman could bludgeon TWO women to death with a nightstick. They each would have tried to protect each other during the attack. It did happen, though, and she's been convicted. She was on drugs and I don't know if that had an impact on her strength, and the grandmother was 88, but I learned from that tragedy that Steelslady is correct.
I agree that the grandparents are overwhelmed right now and may or may not have the emotional and physical wherewithal to take care of their grandson, but maybe he is a comfort to them right now, as I'm sure they are to him.