You are assuming that law enforcers are inept morons!
Nope. But if you no longer have a specific private key yourself, it
can't be seized no matter what rubber-hose cryptanalysis is applied.
Therefore any ciphertext that has previously been captured on-the-wire
cannot be decrypted.
Any message that you still have stored can be requisitioned. As I said,
I don't keep the majority of messages for any length of time.
The mere fact that they are being discussed in a public forum
such as this makes them useless.
You obviously didn't read them carefully enough.