Hilariously I saw an article this week about how Buterin was saying he was worried about Bitcoin because it is proof of work, saying it can't sustain itself and it will be easy to attack in the future. Just shows that all the founders of centralized blockchains are just out to promote their own thing. Now that Ethereum is moving to PoS Buterin feels the need to try to flip the reality and claim that PoW is insecure while PoS is better lol
Perhaps because it would be humiliating to Buterin if he admitted that PoW blockchains are just fine (ignoring the hysteria about power consumption, which is what it seems to be - hysteria) and that a PoS upgrade was never really needed for Ethereum's survival.
All it has accomplished is demonstrating that they will allow [international] governmental interference in their blockchain.