That attitude of, "only the FO can make mistakes" and "I as the captain am perfect" is what causes accidents.

What if your FO was a Public Relations person?

In not letting him make PA's you would: 1. under utilize a valuable resource and 2. miss an opprotunity to learn.

Remember that no one is perfect and that there is always some one out there who is better than you at everything.

There is a reason why there are two (or three. or four) people up there.