Forced me to reread certain parts of the novel. I am a teacher and have seen Asperger's Syndrome in my classroom. At certain stages one might think that it possible autism. However, one that that most children with this syndrome will develop normal intelligence and near-normal language development.
This is not Ignatius J. Riley's problem -- he is a genius whose lanugage development (and vocabulary) far surpasses anyone around him...both of which he liked "showing." In my estimation he had two problems: ADD/ADHD and LAZINESS. Ignatius could not complete anything (including properly dressing himself) nor any task (higher degree for a higher job). Also, he did not WANT to work...he wanted to be cared for by Mother (Irene) or Girlfriend (Myrna Minkoff)...just as long as he could control things. Even when he works at Levy Pants, he wants to control but taken care of by Miss Trixie
Based on the biographical information that has come to like concerning John Kennedy Toole, I feel that there are autobiogrphical elements found in the character of Ignatius J. Riley...both to a degree closet gays.
Hope this helps!