We have a 17 year old lad with some learning difficulties

We have a 17 year old lad with some learning difficulties. He has lived with his foster carers for over 5 years and the plan is for him to remain until he is 18 and beyond.
He has demonstrated over the years that he has an adequate level of independence in that he can attend to his own washing and change his bedding.
He recently had a difference of opinion with both his foster carer and his social worker. He demonstrated his upset by refusing to speak or interact with anyone in a purposeful manner over a number of weeks.
His carer sent in weekly logs and I noticed she had commented a number of times that’ he has not changed his bed this week’ or ‘he has done no washing this week’.
I had occasion to peak with the care and I asked specifically what the situation was and was informed that the young man was sleeping in dirty bedding as it hadn’t been changed for 3 weeks and he must be wearing dirty clothes too. The carers rationale for this was that “he is 17 years old and is more than capable of doing his washing and bedding but is choosing not to so I am not going to play into his hands and do it for him”.
I understood her reasons for this stance and could empathise with her if this were her own child but this isn’t her own child and as a company we have a ‘duty of care’ to all those entrusted to us. For this reason I advised the carer that she would need to provide the basics for this young man, despite this being what he was likely to think would happen. However, we also imposed a small sanction of the withholding of his pocket money until his chores were completed as an alternative from complete compliance.