That’s not what I said. You have to check with each school but many do allow some post high school college classes.
It sounds like your son will be playing hockey in college. What you do need to watch out for is eligibility. NCAA allows 5 years to play 4 seasons (there are a ton of exceptions right now because of covid but that’s the basic rule). The clock starts running when you first take classes, not when you first start playing If he is taking classes in his gap year, the clock starts.