if the hacker had dumped that much NXT on the open mkt, the price would've tanked.
It's not a claim, it's math. Purchasing 1% of all available NXT drives price 10% higher, from observations of the bter market. If you start buying NXT to get a sizeable portion (51% of all available supply), you'll quickly drain all supply at exchanges and drive the price through the roof and still won't get enough.
Yeah, DeathAndTaxes presented the same 'argument' about hacker dumping NXT. Well, my answer was, the hacker could do it in two ways: 1) all at once, which would drive the price to ~200 satoshi and there all the 50m would be bought in 1 day, as at that price and all the way to 200 satoshi would be the daily trading volume of NXT in Bitcoins. 2) gradually, 1m per day which would depress price for a couple of months at most.
The second scenario obviously would hurt more as it would be prolonged, but even that wouldn't be dramatic. After all, whales have been dumping for 9 months now, and NXT has survived that, although the price doesn't go much higher due to that extensive selling. The hacker could not do anything to the security of NXT itself, he could only hurt the price temporarily, and he realized it's best to get Bitcoins which could be mixed easier, even though he would only get a small number of Bitcoins.