You're correct about the forward secrecy. That's what I get for commenting at 2am. I was thinking about TLS where there can be a frequently rotating asymmetric

You're correct about the forward secrecy. That's what I get for commenting at 2am. I was thinking about TLS where there can be a frequently rotating asymmetric key pair. The symmetric key in TLS isn't used for PFS, only for performance. In practice those keys don't actually get rotated almost ever though.