I have heard this for year and it is total hogwash.
Guys like this are usually trying to get the kid to pay them to coach. He is trying to discredit you probably.
It just shows his immaturity and insecurity. Hope your kid sticks with you, sorry you have to deal with this egomaniac.
I have had many sprinters run CC. Have a girl who ran 60 sec as a frosh was all state in CC this past fall and just ran a 62 400 in a time trial. We think she will hit 56-57 in a few weeks. Her speed is still their and she is tons stronger.
I have had quite a few 4:20 milers, all ran CC. This builds tremendous strength for a young runner.
It is not valid to compare Legat to a high school freshman.
Legat has tons of miles under his belt. I think if more sprinters and fast kids ran CC we would see stronger athletes with less injuries and faster times.
Monty