All of those things sound realistic to me. It naturally makes sense that if someone has a problem with shooting any drug and then they are in a situation where they need to inject a medicine (even one as important as hepatitis c medicine) it would logically bring up memories of said drug use. However, I would imagine the doctors are weighing 2 factors such as how sick will he become with prolonged exposure and inadequate treatment to hep c, vs his likelihood of relapsing when exposed to needles. I cannot give any advice on if the risk is worth it but hopefully with support and the proper environment he will be able to work through those urges!! Best wishes!