PoS does not reinforce historical consensus. Every subsequent block in a PoW chain makes the history below it more secure because the cost of reversing it is superlinear in the number of blocks built on top. In PoS, this is not the case, the cost of producing a block is a constant, therefore the cost of reversing history is a constant
But is it really so?
For the record, I'm not technically familiar with either PoW or PoS systems but let's assume that there is only one miner left in Bitcoin and he waits long enough till the difficulty drops. Won't he be able to do anything with the blockchain including reversing transactions? If he will, how does every subsequent block make the whole blockchain more secure then? As I understand it, he will be able to completely undo all transactions. What am I missing, in layman terms?