If he has a tablet computer and/or smartphone, he can use them to pleasantly occupy his time. Also, let him share his status with others he meets, particularly if his parents are around. They'll get the idea that maybe it wasn't a good idea to force his attendance since it's plain he doesn't want to be there.
After I got DF'd I refused to go to any large Witness gathering and even boycotted the book study after a while. Running a steeplechase to avoid contact with other people simply wasn't worth my time and trouble. Your parents should have realized this as well, but clearly are making your brother attend merely for appearance's sake. What a shame! But he can get a small measure of revenge by telling everyone that he can't talk to him because he's DF'd and would be in violation of policy. Other than that, he can't be made to pay attention to the boring and pointless talks so if he has any mobile devices, let him use them during the program.
Quendi