Your brother could try total enteral nutrition (also called elemental, semi-elemental, or polymeric diets), meaning the use of a special liquid diet instead of regular food. It's an old treatment for Crohn's disease that has been shown to work in clinical trials but isn't much used in the US these days (doctors think it's too difficult to ask patients to give up their normal diet for a few weeks). However, it can be very effective, especially for people with Crohn's disease in the small intestine who have severe weight loss. It might be worth talking with his doctor about this. You can drink the formula by mouth, but given your brother's problem with vomiting, it might be better to bypass the stomach and use a nasojejeunal tube (feeding tube going directly to the small intestine).
As to the original question (can't keep food down)--I'm sure he has tried, but just in case--has he tried the traditional chicken soup and saltines?? I know this sounds simple, but sometimes can be over looked. I would also agree to try TNP.
As for trying a different anti-tnfs--the experts (Sandborn, Hanour, Rubin, etc) have done studies (as well as witnessed in practice) that support the idea that just because one tnf didn't work doesn't mean a different tnf wouldn't work. If I were him, I would at least try what is available before giving up. (Who wants to stay on steroids?? Yuck!)
I realize there are many side effects listed in the package insert for anti-tnfs, but ALL "adverse events" must be listed that occured during the clinical trials--That means that even though a person already had a pre-existing problem and that is what they had complications with (or died from), it still has to be reported.
Deciding which medication to take is a personal decision to make with your physician. I strongly encourage you to look at the risk versus the benefits in your INDIVIDUAL case. Just becuase it worked for one doesn't mean it will work for another. And VICE VERSA!
Good luck getting answers and results!