Yeah, pretty much. The power of subpoena to acquire those keys would be trivial.
I think that's one of the problems Perfect Forward Secrecy is supposed to solve. If I understand it correctly, upon connection, the two connecting systems that support PFS generate brand new and ephemeral public/private key pairs for bootstrapping the encrypted connection.
Since those keys are ephemeral, even if some entity collected all the data between the two connecting systems, it would never be able to decrypt that data, even with subpoena in hand: those keys are long gone, as they only existed for a few seconds before being wiped from memory.