for me there are two legitimate options regarding the "unavailable" coins

1) confiscation by some authority (most likely after all the stuff i read) - short and long term extremely bullish

2) he lost the private keys (even thogh supply is much shorter that is extremely bearish due to the public picture that even the oldest exchange cannot handle the technical issues around the currency, how should average joe do that?)

and one option that does not make sense

3) 840k (!) coins are stolen (without noticing), that is almost 1000 coins per day since the time mtgox is operating