What I meant is why do you need to highlight friendlies in green?
Shoot the red ones, ignore the non-red ones. If you want to shoot the friendlies, Boone isn't likely to help you with it.
Because sometimes if you're too far away they won't highlight at all. And when you get closer, if it's a friendly, I've thought that maybe I wasn't close enough for his perk to work.
...So I get closer, and get noticed. It would just help to assist in making out who's who.
Plus, if they're targets you'd like to kill but aren't necessarily enemies, it also helps (Legion/NCR)