I think it's like this: If there is child abuse serious enough to require hospitalization, and the authorities don't intervene at that time, the next instance

I think it's like this: If there is child abuse serious enough to require hospitalization, and the authorities don't intervene at that time, the next instance of child abuse serious enough to come to the attention of the authorities has a 50% chance of being fatal. (So I guess that I'm agreeing with your "worst of the worst" interpretation.) In the case in question, the kid was already in the hospital. So at that point, we're at the "worst of the worst" situation... if it's abuse. So they want to be really sure whether it's abuse. Note well: This is not to defend CPS for the things they did in this case. I am merely saying that this is why CPS wants to look very carefully at such cases.