Mrs B., I hate to be negative and really surgery isn't negative, people generally have incredible positive results and only regret not doing it sooner, but it is possible that it will be the best solution for him. He is young and younger people bounce back so quickly. If I were in my teens or 20s, I would be so much quicker to have surgery. I know it is easy to say that but when you're in those shoes, you want to wait as long as possible.
Life with UC doesn't get any easier, trying to work and maintain stable finances while having this illness is extremely difficult. Honestly, I couldn't do it without my fiance.
There is a user here, Anthony1977, he is a friend of mine (from here) and he had surgery a few years ago after battling UC, none of the meds worked for him. He is an inspiration for me and he is so thankful to be done with this disease. If you want to speak with someone who has been through it, you should contact him, he is vey funny and would relate to a young man having surgery.
On the other hand, you should take your time and let him decide if he is ready. If he doesn't want to have surgery then by all means, try everything you can. Have you considered fecal transplant? You haven't tried the antibiotic combo, have you? How about
trying an antidpressant? I started Pristiq a coupld months ago and about
2 weeks later my symptoms came to a screeching halt. I've recently read that antidepressants can have this effect on IBD/IBD. LDN is another potential option. Have you done allergy testing? SCD Diet? There are a lot of things you can try. Definitely consult with another GI and see what they say.
All I can say for myself is that anything is better than pred side effects.
I hope you are able to get off pred quickly and that he gets into a long remission.