Well they got everyone out without killing anyone which has to be good! I don't know the whole facts so I am not in any position to question the crews actions but will add a bit of info which might be of interest.
If the smoke detectors are like in our 330s they are optical and not heat/ionistaion activated. We frequently have spurious warnings with anything from humid conditions to mangoes decomposing to blame. Mostly we are lucky because the hold is still open but sometimes that is not the case. If there is a warning, the cargo fire extinguishing fires one bottle into the hold when actioned and then (for ETOPS cert) meters in another bottle of extinguishent over the next few hours.
On the ground, a school of thought has that it is better to taxi in, get the pax off and then open the holds to check. In the air, so the line of thought goes, it becomes much more of a coin toss as to what you should do after landing. But coz of that bast*rd, Mr Harry Hindsight, I guess you will be damned if you do and damned if you don't! For me I am delighted that we didn't add any more fatalities to what has already been a horrendous month in aviation.
Cerberus