DS will do what is allowed, but no more, and almost certainly less (including not coming home at all) as he is worried about us.
That is normal for him and his very close group of friends. If he is allowed to meet for a socially distanced walk with a mate, he will go for a walk with that mate, but he would not seek to do any more.
When he is at uni, living exclusively with young, healthy students, he may be more risk-taking (and has in fact had Covid, as have 7/9 of his accommodation bubble, all asymptomatic), but at home with us? No.