There is a difference between feeding and baiting.
Feeding is just that ,
Baiting is feeding with intent to hunt them.
Most states allow feeding, but as others mentioned illinois may not be one of them.
If that's so, would call local wildlife agency.
As for baiting, would check specifics of baiting there.
If your hunting too close to where he is feeding deer you may be in violation of hunting a baited area. Even though baited area is on someone elses property.

Also have you spoken to him about how feeding deer is bad for the population? And he could be doing more harm than good.