As someone mentioned earlier, the flight crew and ramp guys were probably no where near the aircraft. The ramp guys would have finished loading and then they would have been gone. Apparently this flight ground returned (only heard this 2nd hand) and then it appeared to be a rolling delay.
I had a look at the delay policy and no where does it specifically say to notify cargo or the ramp if there is a delay. It is all to do with customer service. If cargo had been notified, they then would have asked the ramp to open the hold.
Nobody does these things on purpose. Believe it or not the ramp guys are proactive with looking after animals. There pax who will pack a large dog in a medium cage, and the ramp guys will berate them in the way they know best.
This case does seem like a classic case of no communication though.
Another recent case of no communication regarding a delay, was MH a few weeks ago. The arvo flight returned to blocks and went at 1000 the folling day. No one told cargo and a B777-200 full of perishable cargo was written off.