You would have to own a majority of masternodes in order to attack instant transaction locks. The cost of acquiring this many nodes (currently about 1.7 million DASH) would be prohibitive, as there is obviously not that much available for sale and even if there was, the price would skyrocket if anyone tried to obtain this much.
AnonyMint wants a system that is NSA/state-resistant (well who wouldn't?), and a system where the state with its limitless resources can buy/bribe most of the masternodes does not pass the criteria. Current holders could become filthy rich in the process but the end result would be a government controlled coin.