Sure it can. His use of remailers makes me think he used full disk encryption. His sudden disappearance makes me think he unexpectedly died (e.g. in a traffic accident), and his family probably did not know his passphrase. All evidence of this person's work on Bitcoin was probably unintentionally destroyed in that scenario, and the people who destroyed it have no idea what their loved one was up to before his death (and will never mention it, for lack of knowledge).