Then you simply don't let the two interact. It's not rocket science. You're over-thinking it.
Deciding to let them interact is totally up to the owner because only they know their dogs. Personally I don't let mine interact, I just don't have any need to, but I wouldn't worry about my maltese hurting my rabbits if I did. They never react aggressively to other animals, even though one of my cats thinks it's funny to attack the maltese (he jumps them and holds them down on the ground, usually while biting them). But they still love the cat and never bite him back. Actually my mom will look down sometimes while walking them in the yard and realize the cat is on top of them again, they don't even yelp:lol:
I doubt Riley or Puppy would ever hurt them either, its just not in their nature to. They've both interacted with the buns a bit, years ago, mostly. Years ago I would take Izzy, one of my old rabbits, riding in the car (he was one of the few rabbits that liked car rides) with the maltese and Riley and they would all sleep together. Teddy is the only exception, he's a bit unpredictable. I don't know how he'd act, he's never been around anything smaller than a cat. Obviously I'd never let him interact with them.