One of us is misunderstanding the definition of perfect forward secrecy. From what I understand, it protects past/current session keys if one private key is com

One of us is misunderstanding the definition of perfect forward secrecy. From what I understand, it protects past/current session keys if one private key is compromised in the future. It does not protect session keys after one key is compromised (e.g. the NSA has Google's private key) and certainly not when all private keys are compromised and the attacker can observe all handshakes etc. Agree/disagree?