If you end up with all fragments for some objectionable content stored on a machine under your control, and law enforcement can apply a decryption/retrieval key

If you end up with all fragments for some objectionable content stored on a machine under your control, and law enforcement can apply a decryption/retrieval key to extract that content while the machine isolated from the network, you're at best going to make yourself an interesting great case over what constitutes 'possesion'. I guess that gets interesting real quickly, since with a descriptive enough 'key' you could assemble almost any digital file from entirely arbitrary data as short as two bits.