An attempt to deflect criticism of one's own stupidity for being unable to discern between satire and reality onto the supposed stupidity of a group, particularly one that is looked down upon by current company, by invoking Poe's Law. When someone is called out for responding seriously to an obvious troll or satire, they will attempt to explain that their failure to comprehend the source was not due to their own lack of reading ability, but because there are individuals within that group that are so crazy, stupid, or devious that it could have actually been legitimate.
Person A: I can't believe this Jonathan Swift guy wanted to eat babies!
Person B: That was a satire, dumbass.
Person A: Hah! Isn't that funny? Those intellectual elites are so cold and inhumane that when one of them talks about cannibalism, you can't even tell if he's joking!
Person B: Poe's Defense? Really?