> letting him talk about his "long mouse telomere experiment flaws" without questions

This requires that the interviewer is as knowledgable as the interviewee (the qualification problem I mentioned). Unless the questions and answers are known ahead of time, it won't be possible to know everything an interviewee will say. Assuming this is the case, how should he have handled that response? Should he not interview people outside of his own expertise? I think one way would be "is there any disagreement?" but then you're left with the same problem.

I think Lex Fridman not knowing much about the history/current state of rat telomere research is entirely reasonable. I think a requirement of knowing the entire context of a person is not reasonable. I also don't think it's reasonable to believe everything you hear in an interview, from either human. "Charitable interoperation, but verify" is a good way to take in information.