This is not an area of legitimate disagreement. There is an objective definition of gratuity, and the use of extreme violence in "Stardust City Rag," however much you may not have liked it or felt it made no sense, does not meet that definition. No, it is not. It is gore for the sake of establishing the emotional stakes of Seven's conflict with Bajayzl. Again: You don't have to like it, or think it's an effective execution of its artistic goal, or think it makes sense as a plot device. There are all sorts of legitimate critiques you could make. But it objectively is not gratuitous.