He's saying that in order to judge someone's ability at something, you need to understand that thing yourself. If you require the candidate to write perfect cod

He's saying that in order to judge someone's ability at something, you need to understand that thing yourself. If you require the candidate to write perfect code using nothing but a whiteboard, you need to be able to read that code using nothing but a whiteboard as well. If the interviewer cannot do this, how is he going to judge the result? Does he know how to run a compiler? Does he know how to run the code? Does he have the skill to judge the output? Is it really a good policy for a company to discard a possibly excellent candidate that just missed something silly that would normally be checked by a tool while you type?