Has this been talked about?
When they started with this "Tim believing Bruce is alive" thing, I was guessing that maybe Tim examined Bruce's remains that would lead him to believe Bruce was not dead. Despite its condition, (flesh burnt off and the clothes remained)there is a lot of information there to confirm if this is Bruce or not. Broken bones, I'm sure there were a few teeth knocked out and replaced, and don't forget the surgery done on him by Thomas Elliott in Hush.
That would have been interesting to see Tim use his detective skills in finding out the truth, but sadly they seem to have forgotten this one talent of his.