There's a lot of following your conscience here. Because honestly, if he refuses right as you are getting on the ride, they are probably going to let your group go and one adult and your son can leave and wait at the exit. Unless you skipped the entire queue due to a wheelchair, they won't know at the other end that you had a
DAS time. So you have to be honest and have a plan of how you will handle it. My son has done the same thing and refused to get on a previously LOVED ride and, generally, if we've walked right through and there's a long line, we will leave b/c the other guests have been waiting their turn. If we waited for awhile in the fast pass line and it doesn't feel like cheating and they OFFER to let us get on, we'll get on. If we try a second time and he refuses again, we don't go on and we don't get any more DAS times for that ride.
Cast members will bend over backwards for us but we try really hard to follow the spirit of the rules because we don't want the benefit to decrease. I actually like this new system better because I think it's more fair to other guests.
Last trip it wasn't much of a problem because he just wanted to get on the people mover over and over and over... lol
Your DAS time won't expire like a fast pass, but you can only have one DAS entry at a time, so if he refuses you need to decide if you're going to try it again or scratch that entry and get one for a different ride.
Make fast passes your priority and use the DAS card for the others. And don't be afraid to ask questions anywhere through the line! We've always been treated very well and very fairly
