I'd also observe that in several instances older experienced F/Os and Capts have failed to cut it when transferring from a low density operation to a high density loco one. The 19 yr old ex cadet who is now 25 knocks spots off them. Many of the cadets I fly with are as bright and capable as the people I flew with in the RAF. A few will upgrade on min time the others will take longer but when they are ready why deny them the opportunity ?
If you are using age as an arbiter you are predjudiced, pure and simple.
What we should really be addressing are the reports that certain carriers are putting people with an inappropriate level of experience/ability in the LHS.