I hate reports like this, no blame apportioned to the ATSB by my saying that, there simply isn't enough information to really know why it happened but losing 2 lives is bad enough, losing 2 lives for no apparent reason is just salt in the wound.
I know there will be quite a few people around Archy who knew the instructor involved at varying levels and will hear about this report and find no real solace from it, if you're reading this, don't despair but if you do find yourself in a bad place then please talk to someone about it, that's what he would have wanted. There might not be any particular lesson to be learned here so use it to take a chance and reflect on yourselves and any areas you think you can improve in then go about working on it.