If they are licensed by the state they have to report to the state.
Not sure how that could have escaped your attention.
He needs a lawyer. A lawyer is the one official who has no duty to report once he is hired.
He also needs to realize that by his NOT reporting he is putting his son and himself in jeopardy.
"So you knew the boyfriend was abusing your son and did nothing to protect him?" Will be the question and "I was afraid of the system" will not be considered a good answer.
Covered in links in #58 above.