No CN coins and in fact no altcoins that I am aware of, have really solved the issue that centralization of mining can cause transactions to be censored. This is an open problem for cryptocurrency.
This is only a problem if the miner can identify which transactions they want to censor by linkability or other analysis. Presuming that you can maintain unlinkability, miners won't censor transactions unless they want to censor all transactions. There's no easy fix for that - if someone wants to spend lots of money suppressing nearly all transactions, you are correct - they can do this.
CN has a viewkey. If the government takes control of the mining because due to centralization they can regulate 51% of network hash rate, then they can require every transaction publicize its viewkey. Effectively the government can force anonymity to be turned off, if they control 51% of the network hash rate.
Being able to guarantee that the mining will always be decentralized, is required to be able guarantee non-censorship.
This is probably the major flaw of crypto-currency.
I do believe I have a design solution and this should be published this year (hopefully). At this point, I wouldn't take my assertion as 100% given, because without peer review and implementation, one has to remember "devil is in the details" and faults could be discovered.