As much as I admire him, Feynman was also no stranger to "Proof By Intimidation." So, skepticism about his claims was always warranted if you couldn't follow them yourself.
This is the difference between engineering and academia--abandoning an incorrect claim or assumption may carry a cost. If you are engineering something, someone might might actually hold you to your claims and start allocating money and resources. So, your claims had better be accurate.
This is part of where the famous intransigence of engineers comes from. "Yes" and "No" are difficult answers. The world is full of "Maybe". Having the intuition from experience to pull the trigger even when the answer is "Maybe" is what makes you a high-level engineer.
Mostly interviews with students or grand-students.
However, I think Carver Mead also mentions this about "Collective Electrodynamics". Feynman got a lot of it right, but there were gaps and he simply bulldozed over people who poked at the gaps--sometimes because he believed it obviously true and sometimes because he wanted to dissuade people from working on something he was already working on himself.
It's kind of a bad habit of lots of academics. Nobody has the time to understand the whole stack of things you stand on, so someone (generally junior) poking at something way down the stack is generally going to get brushed off with "That's obviously true". And, generally, that's fine. But, sometimes it's not and in engineering sometimes it has a cost.
A vital part of engineering is communication. For example, I have calculated the resonant frequency of a microprocessor power grid using a Poynting vector formulation. It was very clever and very accurate, but completely indecipherable to most engineers. It was my job to correlate that with something that fellow engineers understood and trusted.
This is the difference between engineering and academia--abandoning an incorrect claim or assumption may carry a cost. If you are engineering something, someone might might actually hold you to your claims and start allocating money and resources. So, your claims had better be accurate.
This is part of where the famous intransigence of engineers comes from. "Yes" and "No" are difficult answers. The world is full of "Maybe". Having the intuition from experience to pull the trigger even when the answer is "Maybe" is what makes you a high-level engineer.