Ok, ugh.... Wishy and company seem to be derailing from the fucking point.
The anomaly on this whole goddamn issue is that she could've hurt herself and not "omg she wasnt gonna stab her parents, she was cutting her apple", meaning she was more likely to hurt herself than others, it would be tremendously irresponsible not to say moronic to see a child with a steak knife and not take it away from her, sure the whole calling the police issue may have been an exaggeration, but taking the knife away from her, wasn't. You don't need to be "holding the knife against someone's throat" for it to become a potentially dangerous weapon.