The problem of most Proof Of Stake networks is the ledger will be open to attacks if there's isn't any check-points implemented. But if there are check-points being done, then the network is reduced to a "consensus" through "ask a friend", and not from the staking of the tokens itself.
I agree with this statement.
I don't really believe that any attackers would be able to actually confuse the Ethereum community/traders of which is the honest and the malicious chain in practice, however. Do you agree with this?
But it's still a valid point, and why some might choose PoW over PoS. However, if PoW truly has this vulnerability that a rival blockchain could profit from a 51% attack, then its not certain that PoW will remain the more favored protocol, and Bitcoin might want to consider a switch as well.