I don’t know any specific examples of secondhand ideas coming off as original (indeed, he often cites experiments from the H&B literature), but there’s another possible source for the confusion. Sometimes Yudkowsky and somebody else come up with ideas independently, and those aren’t cited because Yudkowsky didn’t know they existed at the time. Drescher and Quine are two philosophers who have been mentioned as having some of the same ideas as Yudkowsky, and I can confirm the former from experience.
I don’t know any specific examples of secondhand ideas coming off as original (indeed, he often cites experiments from the H&B literature), but there’s another possible source for the confusion. Sometimes Yudkowsky and somebody else come up with ideas independently, and those aren’t cited because Yudkowsky didn’t know they existed at the time. Drescher and Quine are two philosophers who have been mentioned as having some of the same ideas as Yudkowsky, and I can confirm the former from experience.