The cases in which B is educated doesn't really matter for the point I'm trying to make.
There are two relevant cases:
1. A is a non-impostor, B uneducated -> B has to trust A, but A's argument seems flawed because B doesn't know of the non-obvious feature that fixes the apparent obvious flaw in their argument.
2. A is an impostor, B uneducated -> B has to trust A, but A's argument seems flawed because their is an obvious flaw in their argument that even B can spot.
From the point of view of B, there is no way to distinguish between these two situations, and so their being uneducated doesn't help them spot the impostor.
There are two relevant cases:
1. A is a non-impostor, B uneducated -> B has to trust A, but A's argument seems flawed because B doesn't know of the non-obvious feature that fixes the apparent obvious flaw in their argument.
2. A is an impostor, B uneducated -> B has to trust A, but A's argument seems flawed because their is an obvious flaw in their argument that even B can spot.
From the point of view of B, there is no way to distinguish between these two situations, and so their being uneducated doesn't help them spot the impostor.