At first, the statement may be regarded as objective because Swift really develops his arguments under false premises.
But, when the writer of the statement includes it "was the most effective way" we can say the author assumes that through the false premises is that we identify the irony, which might be his opinion; So other people can analyze the text differently and identify other aspects in the texts that proves it as a satire.
Finally, the answer is: "Subjective because it is influenced by feelings or opinions"