First of all, it's not coincidence that the craziness at MtGox and the debacle at Silk Road 2.0 occurred at about the same time.   Gox's announcement about the transaction malleability "bug" provided either a method to bleed SR2 dry or (relatively) plausible deniability for an inside job by one or more of the Silk Road 2.0 site operators.

Second, the number of bitcoins stolen from Silk Road 2.0 is nowhere near sufficient to account for the decline in prices at MtGox since then.  The cumulative volume on Gox is well over 100,000 GoxBTC just since the flash-crash that occurred right around midnight on the night of Feb. 13 / morning of Feb. 14, which some were inclined to attribute to the SR2 thieves dumping their coins.  Only 4000 BTC were stolen from Silk Road 2.0. 

I certainly agree that the volatility at Gox is nuts.  Quantitatively, though, I think it's far crazier than you're giving it credit for.  Unfortunately, I am skeptical that any legitimate market activity can fully explain the decline at Gox.  Internal market manipulation by Gox, e.g. misrepresentation of the number they have on hand ("printing GoxBTC"), could explain it.