My question involves workers compensation law for the state of: IL

I'm asking this for my brother who's hand was severely injured in an accident while working at a restaurant. This happened around a year and a half ago. Slipped and fell on a slippery floor in the dish room while carrying dishes and got a deep cut in his right hand that now renders it unable to do much of anything even after a couple surgeries.

After all this time while fighting to get and keep Worker's Comp payments, his old employer offered him his old job back doing light duty, which is something the employer has to keep being reminded of since the supervisors there keep assigning him to tasks he has to remind them he can't do. He's getting few hours and about half the money he was getting while on Workers Comp payments. I can see how this would be a great benefit to WC and the employer. The employer gets some work done for half the cost of my brother not working at all and getting WC payments. I also suspect that they keep an eye on what he does because they had their own doctor examine his injury and concluded that my brother was faking his limitations. They could easily have him on video while at work attempting to please the employer by trying to do what they want, and then show the footage to a judge to "prove" his limitations to be fake, and try to end WC payments or any chance of a settlement.

It seems to me that my brother staying at this job (which he's required to have since it was offered) could only lead to him being denied any settlement, and that the only reason he was offered it is to save themselves money and try to end his WC compensation. Also, by attempting to work with a permanent injury, this job could lead to even further injury. Is there any way for him to stop working there without losing the WC claim?