Other than Ceth's individual experience there's been no scientific study of this that I can find. I'd expect absorption from a 20 minute exposure in a J-pouch to be less (perhaps much less) than absorption when it's taken by mouth. Nevertheless, I think it's an exaggeration to say that none is absorbed. The NIH center that studies complementary medicine doesn't seem to like this stuff at all (Colloidal Silver - https://nccih.nih.gov/health/silver), nor does the FDA.
I like the idea of applying pouchitis treatments directly to the affected area. Killing all the bacteria may turn out to be overkill, but who knows? It would be great if Shen (or another GI who studies J-pouches) could evaluate this scientifically. Heck, I'd enroll in the study. But I'm not going to try it under less controlled circumstances. I guess I'm not much of a risk-taker.