I completely agree with DustyKat, and she makes a valid point that its best to experiment with alternative methods after he learns how to listen to his body.
Crohn's not only affects your digestive tract, it affects your whole body. There are things that a weathered Crohnie will look out for to hint that they need to get in to see their doctor. For example, my eyes swell and my vision decreases.(Iritis)
In addition to what Dusty said, you also have to keep in mind that Crohn's is life-long and your friend's son is only 19. He needs to try and reverse what damage has been done now while he still can, if he can. The way I look at it, I know I have Crohn's in my colon. I know that there is a high chance that someday I will have to have it removed. So I need to do everything in my power to put that off for as long as possible. You can have so much of your intestines removed. And resections, even though they help, they can come with consequences.
In regards to me having a rough time, that is a bit of an understatement. But my problems aren't directly Crohn's related. I started Humira a week ago and I can't believe how much better I feel. Humira is used to treat several autoimmune diseases, one of them being AS. I haven't felt back pain since the night I started it, I see that as a probable sign that I do in-fact have AS. I will be going to a rheumatologist sometime this summer.