No. Generally speaking, proof of stake doesn't let someone transfer other people's funds to themselves just through owning a large proportion of whatever crypto

No. Generally speaking, proof of stake doesn't let someone transfer other people's funds to themselves just through owning a large proportion of whatever cryptocurrency - that's a really bad idea in terms of incentives and also not necessary for it to work - and has time locks in order to try and ensure that funds are actually at stake, which would prevent flash attacks like this one. This was just really badly designed. Letting someone with a mere instantaneous supermajority of money committed decide where to transfer all the invested funds to in a system with flash loans available pretty much guarantees something like this will happen.