Oh, totally agree. And I'm glad Dick took some action (except for brushing off Tim for Damien so nonchalantly, Dick seems to have made all the right Bat-moves to date).
I'm sure the writers have some plan why Tim thinks Bruce is alive but if I was writing it I would go with the obvious reasons: a)Bruce always had a plan - even with Darkseid b)Kon, Bart, Superman, etc. Almost everyone Tim knows has literally come back from the dead and c)Just because the corpse-DNA matched Bruce it means nothing, the whole DCU went through the same thing literally months ago (DCU time) when everyone BUT Bruce and Dinah thought it was Ollie she had killed (turns out to be the Everyman). All Tim has to do is use his own experience to tell him why Bruce is alive, the real question is why is he the ONLY ONE to think so?