This is a difficult situation. I am not that experienced in bonding rabbits so take this with a pinch of salt but I believe Snickers aggression and shyness is rubbing off on Luna. Separating them would be traumatic for them judging by the grooming. My Autumn was an fiery girl when she was young and very highly opinionated but as she got older the aggression turned to affection. I would bet Snickers is an emotional rabbit and is expressing this as aggression, maybe because something is making him uneasy. I would give it more time still, but think about his environment, are the cats good natured? observe their interaction to see this. when they are aggressive, do nothing (but wear protective clothing if necessary), don’t flinch or back down as he may have learned that he can control you. Never frighten or scold them for this will only cause more shyness and agro. Basically, you want to ensure a calm, safe, non- threatening environment. keep interacting with them, regardless of the aggression. Again, I’m not the best person for advice but this is what I sense might be helpful. Good luck with them