No, it's perfectly reasonable to expect him to work his own way from now.
I did it and so did many others. Does he get EMA?
How many hours though?
What subjects is he doing? some subjects require a fair bit of work, some are a pathetically easy at A Level.
and how much do you currently give him?
If you asked his tutors they'd say it's better for him to work a little as possible.
Well this is what is was like for me.
College finished at about 5pm. Got home at about 6.30pm. Had tea, a shower...etc, did college work. By that time it was more or less time for bed.
So if I was working Saturday and Sunday I would have had literally NO free time whatsoever.