In order for Grissom to transfer data to Rose, he would have to use a radio-frequency signal, to allow whatever electronic devices you're using to coordinate with each other. You can put that signal in whatever band you want - short-wave, TV-frequency, microwave, whatever - but unless you've got a really good system for encoding your signal and decoding it at the other end, your transmissions could be picked up and deciphered by anyone in the area with adequate technical know-how. In most of your previous work with communications systems, you rarely ever deal with security or secrecy in their use, and so I concluded that the signals transmitted and received by Rose's visor would similarly not have any sort of security encryption features.
Beyond that, why would a character previously unknown to the rest of the team suddenly be trusted to handle all its communications, no matter how sensitive the information might be??? It's somewhat confusing.
