Swift thinks that the food he suggests is "very proper for landlords". Why does he think this?

This bit of sarcasm is directly related to Swift's feelings that absentee landlord's eat up their tenants lives.... they take their food, their money, and their health, and channel all of these things right back into England. Irish tenants were treated as little more than slaves, and Swift is insinuating they may as well devour their tenants children as well.