Seems strange, how about having a passion for what you do? For me, that's the most important thing. If I didn't like music working on the gear would be much less rewarding. I think the best designers measure AND listen!
How do you know whether he's passionate about what he does? What listeners do when they listen to music is totally different from what designers do when they design gear. It's like telling the neurosurgeon who is about to save your life based his many years of specialized training that you only want a surgeon who has experienced the same surgery him/herself. How do you know whether that Doctor really cares about what he/she does?
Btw, I've talked to more than one audiophile engineer who feels the exact same way as described in the OP. One of them publicly claims to be a big music lover on his manufacturer website. However, he told me at RMAF several years ago that he doesn't listen to music and doesn't consider his customer's feedback about how something sounds. He's a very highly respected digital designer.
How about lawyers? If you got charged with a crime, would you limit your search to only lawyers who were also criminals? Better Call Saul, "When the going gets tough . . . you need a criminal lawyer."
[video]https://youtu.be/JNMQqh1ovlM[/video]
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