This paper is the one and only source for every claim from the past 10 years that "scammers make mistakes in scams on purpose." Crucially, no actual scammer or former scammer or even acquaintance of a former scammer has ever corroborated it. The paper itself is pure speculation.
If anything I think that paper serves best as a reminder that just because an idea is clever and logical, that doesn't necessarily mean it's true.[1]
[1] As another example, see https://en.wikipedia.org/wiki/Nuclear_Gandhi
No. The paper is about reducing a set, as far as I understand. It's not about mistakes. It's about the deliberacy of basically squeezing out the individuals who are vulnerable and who do not see the signs of being scammed.