All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
The best approach is to be moderate in such a matter, meaning that one should deal with it without excessiveness nor negligence.
If someone at this age is given freedom without any limits, he may become corrupt and corrupt other people, and if he is completely forbidden from practicing some activities, he may become somewhat rebellious, stubborn, and delinquent.
Hence, in our view, your opinion is valid from one perspective and the opinion of his family is valid from another.
It is better to reconcile between the two opinions by allowing him to practice permissible activities which he needs and that you choose the suitable environment and good friends for him, and if it is possible that you or another family member accompany him, then that would be good.
What remains to be said is to stress the importance of guiding this young man in his religion and to teach him the Aqeedah (creed) of Islam and its morals and etiquette. If it is possible to take him to an Islamic center that is concerned with the youth, then this would be good for him, as by doing so he would combine the good of this life and that of the Hereafter.
Allah knows best.