What's they do about the big BTCs account?
Sell high buy low, make some money, since few people will withdraw BTCs.
Sell high, buy low - that sounds about like what everybody else does as well - no need to imply Mt. Gox.
Besides, there was no single 350k BTC sell-off - the largest trade that clearly seems to be from a single account is around 40k BTC and that's pocket change for some at the recent price levels.
According to the statistics, no body owns more than 50k BTCs except MtGox.
That reasoning is flawed.
Yes sure, Mt. Gox _could_ trade on their own exchange but you have absolutely nothing to back up your accusations.
Don't get me wrong I'm all for more decentralized exchanges and eliminating single points of failure, but there's no need to accuse Mark of outright fraud. He has done a _lot_ for the community and he is arguably taking most of the heat from the regulators.
So please, unless you have something more substantial, refrain from such wild accusations.