I have had CD since I was 15. I am now 36. I missed my last two years of High School but got home study and graduated on time. I went away to college and had jobs while there. Since graduating the only time I wasn't working was when I was out of a job. I have done many things from cooking in a kitchen, customer service at an airline, Barista at Starbucks, and even worked on a cruise ship in the galley.
My point is everyone is different. I have been one of the lucky ones that has a mild case and I won't let it slow me down. I always tell my employers about my disease so when I do get sick from it or have to do a colonoscopy, it won't come as a shock.
I do have a question for you though. How long has your son been on Remicade? If he isn't better then maybe it isn't working and he needs a different drug. Also, has he looked into jobs that you can do at home?
I hope he feels better and good luck to him.