it kinda is. in the first episode they talk about chief and the unsc is talked about many times. it might not be canon but i say it is part of the universe. but thats only my opinion.Well, not everyone watches RvB. I personally dislike it, so I didn't know what you were referring to.
But, what would that mean? The question was what would you be in Halo universe... referring to Caboose, so you would want to be Caboose or what? Kinda doesn't fit as RvB aren't part of Halo universe.