Most of us (clan members) already keep unified lists of friendlies and enemies outside the game, so this would be nice to have, especially if the holodisk export/import is implemented, althought that can come at a later stage of course.
Mind you, I never said player name input should be the ONLY way to tag, but it sure comes in handy at times, especially if you want to change the status of someone or a group and the only time you will be meeting them next is at a battle, at which (and other) point(s), the current system fails.
Perhaps the pipboy module can be appropriately named "FOF (FriendorFoe) module.