Well, you can either make yourself crazy trying prove or disprove a diagnosis and never get a clear answer, or you can accept chronic pouchitis as a diagnosis and just take it from there. Go with what works. Treatment is essentially the same based on signs and symptoms, regardless.
I know it does not seem very scientific, but sometimes there simply is no clear cut answer. Remember, you cannot completely rule out Crohn’s, as diagnostic certainties are often not present, at least not with today’s diagnostics. This is where the skill and knowledge base of your doctor comes into play. There is such a thing as Crohn's of the pouch, without other involvement.
Personally, I’d be pleased that my disease is confined to this small area (for now). Perhaps with effective treatment, it can stay that way.