Personally I don´t think you can expect rational reactions in a situation like that. I try to imagine the chaos of the whole scene, the horrid message- it would take some time to really sink in.
His accusation that the police had killed everyone wasn´t rational either.
His first reaction was anger, and true, normally you have denial first, but no two people react the same.
P.S. I am not an expert on this, but isn´t shock and grieving different? There are these "Five stages of Grief", where denial is the first reaction, and anger the second - but what about shock?
Alias, when I was training we referred to it as loss and bereavement. the general assumption is that we grieve for people but if you've ever lost a favourite book/piece of jewellery/pet goldfish/purse, that dull ache, which most of us experience every time the lost item comes to mind, is no different from that gut wrenching pain we experience when we grieve for our loved ones. It is grief.
The Kubler Ross model gives us 5 stages: denial,anger, bargaining, depression, acceptance (all of which can be broken in to sub sections) and as you say, the stages don't conveniently go 1 through 5, they can take place in any order and for any period of time. There is no set time, the process CAN go on for a life time. Time DOESN'T heal, it just puts the pain in a place where we can hopefully cope with it better.