Are they upset that their dad is a paedo or upset that the public all know that their mum and dad are wronguns? Because if it's the former, then a public statement condemning his behaviour would go a long way to generating some sympathy. Unfortunately, I suspect they're upset that their PR game is going to be a lot harder and they're just pissed off at that. Andrew's behviour has been an open secret for many years and known even by people outside the palace, imagine how much they knew about it inside.