You worry too much.......the boy has to learn sooner or later.

And don't give him a big knife - simple small pocket knife is all you need.

I teach gutting in our Hunter Ed classes and have students as young as 9.

As a suggestion use what we do with Hunter Education Program. It is a method called The EDOC System -
Educate - Demonstrate - Observe - and then Congratulate.
Sounds as if your boy has witnessed the first 2 for quite some time. Now is the time to Observe - correct if needed but do not to get upset or holler - but find ways to praise where you can - and then when ever he is done Congratulate.

We all know we learn from our mistakes.

And as many others have written - you know your boy, and know when it is time, we are just feeding you ideas and suggestions.....

JW