The government will have a hell of a easier time forcing masternode owners to give themselves in or just taking down the servers the masternodes are hosted on, than forcing users of Monero or Zerocash to do the same. It's a hell of a lot harder for the gov to do that to users of coins that dont utilize external masternodes to provide anonymity(monero).
If an evil Govt shut down a VPS, the same masternode can reappear in another country as soon as an instance is provisioned. Minutes or hours. No fuss, no muss.
For non gov entities, I suppose finding another flaw in darksends rounds, or a flaw in masternodes themselves would be much more plausible.
What does that even mean?
If the coins are held on the masternode and not a cold wallet, that masternode isnt reappearing anywhere. The gov can just take control of the servers the masternodes are hosted on.
Someone found a flaw in darksend and was able to deanonymize a transaction back in late 2014, such a thing is much more plausible IMO for a non gov entity.