From the paper the article is based on:

Accordingly, individuals best suited for high-stakes leadership, judgment, or executive roles are likely to be between 55 and 60—and unlikely to be younger than 40 or older than 65

I wonder if the authors are approaching or within that age bracket and not yet ready to admit that they're falling apart.

Traditional cognitive abilities show diverging patterns as people age. Fluid intelligence, which includes raw reasoning skills and memory span, peaks in early adulthood and falls steadily afterward. Crystallized intelligence, which relies on accumulated knowledge and vocabulary, continues to improve over the adult lifespan and often remains high into a person’s 60s.

Personality traits also change as people mature. Conscientiousness involves being organized, disciplined, and goal-oriented. Emotional stability involves managing stress, staying calm under pressure, and showing resilience. Both of these traits generally increase from early adulthood through middle age, making older adults more reliable and composed than younger adults.