That's exactly why I think that he expresses 'surprise' at Tom!

"You surprise me Tom! We pulled something off many years ago that was unheard of! OUR history has taught us that we can kill anybody! We did it once and we can do it again! Right Rocco?"

Perhaps he said it making it appear as though he was making a much broader reference. But I believe that his underlying message was to reference what they were able to do once before, more than anything else, without coming out and actually saying it.

At least that is what I always took from that scene.