i somehow fail to understand all this ...
we remember the reports where the search teams received pings which
a) were on the final arc of handshakes
b) were recorded, anylysed and verified to be from an ULB.
c) started to fade out at the 30 day battery limit.
knowing the very limited range of the ULB pinger and using common sense to realise its to much concidence that a b and c together can be anything else than really mh 370 could lead to say " deepest respect you aussies - you really found the wreckage" ,just send the auv to confirm.
they did and... nothing ...
so in this mystery i see only two explanations
a) all the rumours are false, the pings were never from a blackbox ULB and they search in a more or less complete wrong position
b) the pings were from a blackbox ULB - and since no other aircraft crashed there last time for sure it can only be mh370 - but the bluefin is much more limited than released to media and simply failed to scan the wreckage even when it was in the right spot.
i do not see other explanations - normally when you hear the ULB you have found the aircraft.