I'd guess that authorities would also have issues with situations where one purposely encrypts a hard-drive and disables decryption until later / confirmed safe

I'd guess that authorities would also have issues with situations where one purposely encrypts a hard-drive and disables decryption until later / confirmed safe by a third party. At the very least, that is what "Possession of encrypted data whilst being unable to decrypt it" sounds like. It then becomes a grey area between having been sent encrypted data, and having used the previously mentioned scheme to avoid decryption. I also wonder how this interacts with the new 5-tap SOS function on iPhones.