I recommend that he exercise, work his core on an exercise ball, stretching and and can use KT tape on his upper back.

Ergonomics are going to be very important. Make sure he has a good chair. His knees and hips are bent at 90°, he is sitting tall, elbows are 90°, and wrists are in a neutral position. It is also super important to take breaks after 30-45 minutes to get up, move around and stretch to relieve any discomfort.