Question about discrimination?

My son has attended a local college for the past three years taking a mime course. The course goes for 5 weeks and is open for kids 5 to 18, my son has aspergers, this year the staff informed me that if my son is attending he will 'need an adult supervisor the whole 5 weeks. Can they do this and refuse my son if I can not find a person to be with him. They have not required this in the past