The sentence about landlords because it is against the upper class and addresses that upper classes take advantage of the lower classes to get what they want
The correct answer is: I grant this food will be somewhat dear, and therefore very proper for landlords, who, as they have already devoured most of the parents, seem to have the best title to the children.
Swift is targeting Protestant Irish Landlords (upper classes). He clearly speaks about them in very negative terms since they oppress Irish Catholic tenants just because of their religion:
Here he says that these landlords have exploited and abused their Irish Catholic tenants and that naturally they can do the same with their children (the humor is meant to criticize the landlords). Swift is actually criticizing the fact that landlords have taken everything from their Irish tenants, only the children are left but not for long.
