I'm not familiar with anything stating it in 4A. I know Unwired (only because I'm re-reading the book for a game) states that Peripheral nodes (Unwired 48) generally only have Administration accounts - but they don't get the +6.
Hacking Electronics (Unwired 103) also says devices mentions it again, sans the notation where they don't get the +6. This section KS also a little dodgy on what defines a 'device'.
However, seeing as the Com is the hub of your PAN, and only accepts 1 persona, etc (Standard Node rules), I see the logic in making it administration only.
The kicker is, my Unwired book is only 4, and my rulebook is 4A. So I can't promise I didn't miss something.