I have to agree with the teaching proper iron sight use until he is proficient with them. Then, a scope & even then, maybe a "red dot" type if you want him to have a "cool" factor gun.
In teaching a new shooter, it is important they learn the basics before moving on to the next step. The eyes can not focus upon 3 things at once, (Rear sight, front sight, target.) So, teach him to focus on the front sight as the rear sight will be a little fuzzy & the target will be the fuzziest. Next, use larger, close in targets. Also to make it fun, add in some reactive targets, (If the local range allows them.)
Once he learns the basics properly, he won't grow up & learn he needs to break a bad habit & re-learn how to shoot. (Like I did.)