You have a malignant brain tumor and your HMO must choose a surgeon to perform the surgery.
The HMO has two choices: one is a world renown neurosurgeon who has removed 150 of these tumors and is widely published for his state-art-the-art techniques and skills at saving patients' lives.
The other choice is a competent general surgeon assigned to small city hospital. She has never removed a brain tumor but assures the HMO that with a little bit of study and reading she is confident she can get the job done. The HMO chooses her and explains, "She may have an ordinary intellect and comoletely lack experience in operating on brain tumors, but she's a hard worker, knows what a scalpel is, and we like her a lot."
Do you feel good about the person who is about to crack your skull open?
The problem with the example you give is that if we apply it to the situation here, you are suggesting that she have experience as a supreme court justice to qualify to become a supreme court justice.
It doesn't work that way.
To answer your question, though, I'd select the specialist.
The skill, and potential of the "world renowned neurosurgeon" was recognized by someone who knew her before she removed her first brain tumor. She was recommended by that person, and some patient trusted her to perform that first surgery to remove that particular type of brain tumor. Then came a second patient, and a third, until she had performed the 150th, and had become world renowned.
I'm remembering that Elvis was told he would never make it in the music business. Rush Limbaugh was told he would never make it in the radio business. Ronald Reagan was called a second rate "B" movie actor. George W. Bush has been called too many denigrating names to remember or repeat. Justice Clarence Thomas was called "a token", and worse, when he was nominated to the SCOTUS. They each proved the naysayers wrong, and many would say they are among the very best. OTOH, I could list a number of people on the world stage who have failed to meet the challenge of applying their supposed knowledge to the test of reality. Bill and Hillary have had more said about their proclaimed superior intelligence than any I can remember in recent history, but....