I didn't read this as a bias against significant prior challenges, in childhood or after. I certainly had such challenges and I've always thought most people have. Since the author's stated goal is identifying high potential, early career candidates in the absence of prior success or obvious metrics, it seems essential to look for resilience.
To me, understanding how a person has contextualized and integrated prior challenges into who they are today is a key personality trait. So much of attitude is "the stories we tell ourselves to explain what happened to us." In my case, I've always felt my childhood had "some pretty rough patches" but in total "it wasn't too terrible." Yet, the few people I've shared the details with are usually aghast at how institutionally abusive it was. I don't deny the severity of it but it's pretty revealing about my personality that I don't now feel emotionally wounded by what happened. Perhaps it was just my coping mechanism but I've always felt "that's just shit that happened to me, it doesn't define me."