I am not super surprised that a coach at a school your son applied to reached out to your son. Coaches with successful teams do this constantly.
But your question is also so vague it’s kind of hard to have an opinion. I don’t really understand what your question is. What does it matter if it’s standard? Maybe your son is a great athlete. Are you asking if a coach at a well name school is sketchy? The answer is probably no.
Coaches literally do tons of things that “aren’t standard.”