Excuses given are along the lines of "I never win an argument with you" and "you've studied it a lot more than I have, it's an unfair discussion".

Suppose there's some issue about which I'm not an expert, but I trust experts in the field who hold position A. If I come across an expert in the field who holds position B, I might decline to talk to them about this issue because I trust the A expert's ability to make a decision on the issue more than my ability to make a decision on the issue.

When is that a reasonable thing to do?