Yes, I think that is what happened. When they left the island, there were less than 30 people left and no students in the school which probably means the only ones still there were older.
The younger ones had probably already moved. I remember reading that after Culloden, the English sent a boat to St. Kilda thinking Prince Charles might be hiding out there.
The islanders didn’t know who the Prince was, they also didn’t know who King George was.
Ignorance really can be bliss. ;-) But that had to be the sort of rough life most of us would prefer to escape.
The people of St Kilda’s depended on eggs from sea birds to supplement their diets and had done for so many years that they had pre-hensile toes from centuries of climbing the cliffs raiding bird nests...feet that looked more like a second set of hands. I seem to vaguely recall that after St. Kilda’s population was relocated, that the island was used by the government for chemical experiments, and I don’t think it is permitted to visit the island any longer.