Such miner CAN NOT violate ANY consensus rule, but he can add his own rules by refusing to mine on top of blocks that violate the additional rules, thus censoring the network.
However, this is assuming everyone else just sits and lets it happen. Others can add more hashopower and dilute the adversary. Or, they could introduce some weak subjectivity on top of PoW: https://blog.ethereum.org/2014/11/25/proof-stake-learned-love-weak-subjectivity
Ultimately, all blockchain networks are secured by their economies. People who are part of those economies will not just sit and wait while their beloved network is under censorship attack.
