You are confusing state income tax residency requirements with Internal Revenue Code dependency definitions, maybe with some school rules regarding in-state tuition thrown in.  For Illinois state income tax purposes, he is still a full-year resident, unless you want to claim he is a part-year resident and not include the time he was in Tennessee.  He has no tax nexus with Indiana.  

This reminds me of my college days in Illinois, when I helped roommates fill out their state income tax returns.  I had no training but I must have been good at it because they received  refund checks for the amount shown on the return, and then a month later received another refund check for the same amount.  I remember some connection between this and Paul Powell's shoeboxes, but you have to be of a certain age to remember the Illinois politician whose unexpected death led to the discovery of $800,000 cash squirreled away in various places he had stayed.