Privacy is whole different subject here, you used terms wrong. Public ledger can also be annonymous.
Well to be fair, he didn't actually mention that he preferred private ledgers. He specifically said that he prefers the privacy properties of Zcash, though he did say Bitcoin's public ledger is its biggest flaw. Some people just automatically attribute privacy to private ledgers, I guess.
Either way, if Bitcoin is facing a crackdown for criminal activity, I can only imagine the firestorm that fully anonymous cryptos would have to brave once they become popular enough.