I don't have a source, I've made those assumptions after countless conversation with various actors across the blockchain space both from PoW chains and PoS ones.

It's not much about security but more about permissionless, neutrality and resilience. PoS isn't insecure but it's less resilient and tend to have neutrality issue that we don't have seen yet on Bitcoin PoW for exemple.

There is different things here. First with PoS you don't have a link to the real world, atoms and stuff. You don't really have a physical cost to secure the network, you don't have external factors like you have on mining farms. The competition is completely different where you have to find the cheapest energy source and the most stable places to mine. In PoS validator gets richer and gets more influence, in PoW this isn't exactly the case due to physical reasons.

If for some reasons like a bug or a global disaster and that all the nodes went offline when the validator start to come back online they will have to communicate and choose what is the real chain. With PoW miners will simply mine the longest chain as it's the consensus. Bringing more resilience.

Also in PoS like on Ethereum an issue is centralization of the validator, on PoW this is more about concentration while not an ideal thing this isn't as bad as Lido and AWS centralisation.