LOL. Here's the attack vector Evan created out of ignorance, stupidity or pure not giving a fuck.
The easiest attack is to buy masternodes and ddos attack competing nodes until you own the traffic. Evan claims it's financially implausible, but ignores that nodes are most profitable when there about a 1,000 masternodes (he has a ROI graphic on the dash BCT thread that underscores this). He also ignores that the attacker would be pulling incomes from these masternodes--given that most are held on corporate servers underlies that no one knows who owns them outside of the host and the owner. He also ignores how motivated an attacker may be, that he or another masternode operator might comply given the right circumstances (threat or lawful compliance) and how deep LE's pockets are--silly, dangerous, stupid.
If you trust that system knowing the flaws, you deserve whatever comes your way--except maybe being linked to pedophiles--can you show that link on your explorer?
DOS'ing masternodes doesn't reduce the anonymity set of the transactions or coins mixed before the DOS. If the masternode count drops 50% for example all of a sudden, mixing coins at that moment is not a good idea. It was already suggested a year ago or so that the wallet would take care of this and protect the user during the network downtime. It hasn't been implemented yet afaik, DASH must grow at least 100x at minimum before this (an appearance of such a motivated attacker) would become even a possibility.
DDOS is to control the majority of nodes, not to directly reduce the anonymity set--though by doing so while monitoring the nodes you posses would break anonymity--which was my point.