Why? PoW can only afford to be attacked twice. It even has a name: “spawn camping.” In proof of stake, this is pretty easy to defend against repeatedly.
edit: Blacklisting UTXOs is entirely possible as I mentioned, and as I said, it should be achievable by soft fork. This would be the proof of work equivalent of slashing. I have a hard time believing Vitalik doesn’t know this. Is he being dishonest? I don’t know.
You can target the UXTO so that their value in crypto starts back at zero. But because they still have the mining hardware, they still control 51% of the hash power that secures the network. They can just mine from a different address and it won’t be clear who to target until they once again begin to produce majority blocks on the chain. This way they can continually attack the chain and render it useless.
When you burn a PoW miner’s crypto addresses, you aren’t burning their capital and stake, because it’s in the form of mining hardware, not tokens. When you burn a PoS staker’s crypto, you are burning their capital and stake which is in the form of tokens.