My own theory for what it is worth is that the IAF were aiming for the launch site at the cemetery and got the hospital instead. It doesn't matter really, those that blame Israel will continue to blame Israel, those that are blaming Hamas will blame Hamas.
Lines have been drawn in the sand (plenty of that on this thread) and the fighting will continue. Hamas won't stop launching rockets, Israel won't stop dropping bombs.
TBF to Abbas, Abdullah and El-Sisi there isn't really much point in meeting Biden other than photo-ops. At this stage he will listen to them and tell them he understands their concerns and promise to pass them on to Netanyahu. He will probably even do so but at this stage he is not going to tell him to stop.
A ceasefire at this point is effectively a victory for Hamas, they will have given the invincible Israeli's a massive kick in the balls and lived to tell the tale.