Can support workers stop poor choices

My son is 25 with severe autism, learning difficulties and other diagnosis. 

Last year he moved into supported living with full time support. The staff are all lovely but my son’s world has shrunk to virtually nothing. 

Before he went he had been to college, got qualifications, had friends and got up to all sorts of things. He’s now dropping all his hobbies and interests because he tells staff he doesn’t want to do them and has become nocturnal because he won’t go to bed and won’t get up. And no one is making him. Staff keep telling me it’s his choice and they have to support his choice. 

When he comes home it’s become tricky, but not impossible, to motivate him but he has clearly got the message that he can do whatever he wants with no boundaries!

He has lots of things in his care plan that aren’t being done because they say he’s choosing not to. Last week he chose not to go to a work placement he loves, because he said it was too cold - so they let him sit in his room on his ipad all day. He’s missing Drs appointments because he says he doesn’t want to go.

Is this supporting people with disabilities to do whatever they want true? Where does it come from?  What if he chose to jump in front of a car or wander naked onto the beach? 

At the moment he seems quite happy to be doing nothing but what happens when he starts to get bored and frustrated? He simply doesn’t have the capacity to understand the consequences of what he’s choosing to do - or rather not do  

Have his staff got this right? how can I strengthen their responsibility to encourage him robustly to do things?  His residential college managed - with him and all their pupils.  What legal structure are they following that his supported living people aren’t?  It all seems mad and heading towards disaster