> we are absolutely FILLED with greybeards. I's say that the average age is pushing 40 and the average tenure with the company is 10+

Taking your observation in isolation, there are two implications:

1. that those 40+ years old were, in average, hired when they were in their 30s, when they weren't grey beards;

2. a possible factor that causes their long tenure is that they now struggle to find other jobs.