Yup, that image for for fluff, youknow showing all the traitors together at a pivotal point near the end of the heresy, and giving a representation of some characters that weren't shown, but were mentioned elsewhere, or adding additional characters to bulk out the fluff. Add imagine it'd be a either a marine possessed unwillingly at some point or the corpse of a marine, as I don't recall there being mention of any Blood Angels turning traitor during the heresy. He's there for fluff and to show that those outside the traitor legions could fall for whatever reason or something like that (plus he's a great model to convert

).