any kind of dump whether big or small can never cause a bear market. it can only cause a drop and drops are temporarily decrease in price not a continues tendency to go lower and lower (aka a bear market).
not to mention that the sells started long before the bear market or before any significant drops even! this whole thing about Mt Gox trustee and the bear market and all the rest of the panics that follow are silliest reactions that the market is showing these days. it is exactly the same as last year when they said "China banned bitcoin" and price dropped 4 times and then the same as each time they said "bitcoin will split and die" and price dropped a couple of times! it is FUD, nothing else.