The movement is still young. People introduced in college are still only in their mid-30s.
Generational differences in moral partiality vs. impartiality. Moral impartiality is still not widely accepted.
Age discrimination
A good amount of funding is geared towards those coming out of post-grad.
Technological advances are typically adopted by the younger generations first (AI risk).
Being underprepared for retirement. Not everyone can (or wants to) be subject to a decrease in compensation, especially in years where retirement savings need to be accumulated.
I'd agree that his experience would be useful to many orgs, but staying in his current career and earning to give would have more impact than job searching for year upon year, with lower likelihood of success as he ages - if his ultimate goal is impact.
Someone who is 57 years old with decades of specific industry knowledge seems like a perfect candidate for earning to give. Have you considered that route? You can still stay informed on EA and participate in events and groups, while working in your current career.
Here are a few reasons off the top of my head: