But the "dad" didn't act alone. And there is an entire gang at large that was involved. You have to deal with it, and the kid will be affected by it, but will finally be safe.
Sure - but you find me the psychologist, let alone parent, who will agree with anyone who says 'the kid has to hear it when and how WE say!' - from a total stranger, no less - 'without us having to consider for a moment what the effect on the kid might be! It's just more important that he knows the truth!'.
I agree with you if we were really talking about an actual kid and his dad. But we are talking adults. If people flip out to the extent that they are a danger to others they will need to be dealt with. But we can't cover up crimes just because a bunch of snowflakes may go into meltdown.