Under normal circumstances, when the rescue effort is called off, it is time to bring in the bulldozers. You could have the rescue period go on forever! Surely, there is one person buried with tons of food and water! But, there are all those disease-causing bodies buried under open rubble, and the rain will wash out and contaminate everything. It is time to bury the trapped bodies.
They've done that for most recent earthquakes, like Italy. The heavy equipment comes in and takes down those dangling structures, that could kill people with the next aftershock, and they clear out and pile everything in a giant mountain of burial rubble. But there's no heavy equipment here! They can't do anything!
So, the rescue crews can be as stubborn as they want, and refuse to leave. Only the threat of disease might start to keep them away. The next phase of recovery doesn't happen until they can call in the bulldozers.