The irony of this passage, and in Swift's treatment of the poor in general, is neither simple nor straightforward. His compassion for these people is mitigated by a strong sense that people ought to take the initiative to help themselves out of their own difficulties. Swift's language here plays on the popular judgment of beggars as lazy opportunists. While Swift does not entirely dissociate himself from this opinion, his purpose here is to show the complex web of social and economic realities that supports and perpetuates such a situation.
The speaker is a Protestant and a member of the Irish upper class. While he professes sympathy for the plight of the poor Catholic population, he also holds a fairly contemptuous opinion of them. He takes great pains to enumerate the advantages of his proposed project for the wealthy, who would presumably be called upon to implement it. Yet Swift's irony implicates this moneyed class for their monetary greed, their personal indulgence, their unflagging attention to their own self-interest, and their indifference to the state of the poor and the state of the nation as a whole.
The "proposer" is notable for his vanity, his cold-heartedness, and the ruthlessness of his logic. He represents the hypocrisy and superficiality of many would-be reformers, whose seeming benevolence masks such impediments as prejudice, intolerance, sentimentalism, and hyper-abstraction. His reductive handling of suffering humans as statistical entities and economic commodities is what makes him most unappealing, in spite of the calm and reasonable tone of his argumentation.