If the coins were not stollen recently and entered the bitcoin economy long ago, then the missing 750,000 GoxBTC is bullish medium and long term, because the effective monetary base of bitcoin just decreased by 6%. If 20% of those who thought they had coins at Gox, buy new coins (and move them to cold storage this time), that represents 150,000 BTC of sudden demand.
Theories based on an influx of money to buy lost coins are wishful thinking at best.
Where does the money $75M for the 150K coins come from? People don't re-buy lost investments like that - the money invested is gone. Add in the likelihood that most of the stolen coins were mined, not bought, which even more unlikely to be re-bought.