Swift is concerned with the problem of poverty in Ireland. In this passage specifically, he is concerned with those people who are "aged, diseased or maimed." He knows that this is of great importance to both the people themselves and to the well-being of the country.
However, Swift also believes that many others are not concerned about them in the least. He mocks these people in the passage by using satire. He calls the sick and old people an "incumbrance," implying that this is the way they are seen by some. He also tells us to not worry about the situation too much because these people are constantly dying. He says this in a positive way, even though it is a horrible reality. In this way, he continues to display a satirical intent.