If he is competent enough to make his own decisions and get around on his own, I am not sure what violations you think they committed. At least you feel that he is competent. As he was able to be contacted by them, have the applications filled out, take the tests, and enrolled in the school without you knowing or raising any objections.
Also, as far as I am aware the ADA mostly involves discrimination AGAINST a person with disabilities. How did they discriminate against him if they enrolled him in the school and are trying to provide tutoring? Had they actually denied him this education after passing the "proficiency" test, he may have actually have been able to turn around and sue them for discrimination.
Also, except for the cost, what makes you think that a Community College would be any different? Have you been to one lately? Just trying to get a class can be an experience...not a pleasant one. If he struggles at a CC how easy do you think he would find access to tutoring? Do you think he is always going to get Instructors or Professors who will spend extra time with him when they have hundreds of other students.
I am not defending ITT or knocking Community Colleges. Just giving something that you need to think about.