But how do you calculate the confirmations required for pure PoS+MN blockchains?
For example you require 125 confirmations on Zenzo, with 1 minute blocktime that's 2 hours wait time!
With the supply in circulation and the current price, it'd cost someone 148000$ to attack the coin with a 51%, so don't you think that's at least secure enough to drop the confirmation time to about half of what it is now?

Semi-dead PoW coins are easily attacked if you point Nicehash or a small farm or a couple of ASICs on their network, those are really easy to attack (though pointless profit-wise).