This is debatable as Collateralized capital is perceived capital (Not tested in free market) valued by a community (might be small), and security is directly proportional to the value of that capital (token deposit) against the proven capital(let's say $$) but in proof of work network security is directly pegged to a proven capital.

The assumption is PoS that network token is capital is debatable as it only comes into play when network is up and purely a subject of speculation but this is not the case in PoW.

Using the network token as a security deposit is a utility, justifying token existence, there is real possibility that token may not have any other utility in the future.

PoW is must property when you are creating capital, ex- Bitcoin, though other use cases might suitable for PoS.

PoS can become more powerful when it can use an already proven capital as stake rather creating its own token.