I don't know enough about Mitchell to offer any defense of him, or even if it's warranted. The original post I was responding to was:
> Well to be fair, the US Army Air Force didn't sink any battleships. The battleships (eg Musashi and Yamato) were sunk by US Navy planes
I was just pointing out that reference to the Army sinking battleships was almost certainly a reference to the Mitchell debate, not a claim that the USAAF was regularly targeting capital ships during WWII.
The only other thing I would say is that, everything you say about Mitchell may be true. But Mitchell's premise was still correct that aircraft can sink capital ships. His demonstration may have been rigged and an insufficient proof of it, but the premise was clearly shown to be true through the course of WWII even if the sinking of Virginia and Ostfriesland was rigged. (And thank you for bringing up Ostfriesland. I didn't know about it so now I have a fun new thing to learn about.)