I had not considered this. I often saw 'pedophile' as just the technical term (abused though it is). I think 'pedo' is much more offensive than 'pedophile', like 'homo' to 'homosexual'. That being said, 'homosexual' was once used as a slur too. But you may be right in that the term is just far too tainted to ever be recovered for what it truly means now.
What I do think is definitely offensive though is 'nonce'. I think this should definitely be on the same level as the 'n' word, and it even starts with 'n'!