In most novels and stories, there are several types of characters, including the protagonist (the hero), the antagonist (the villain), the stock character, and others. When we discuss a writer's characterization, we often distinguish between "flat" or two-dimensional characters and fully-realized, "round," three-dimensional characters. In "Rose for Miss Emily," for example, Miss Emily and the townspeople might be considered to be fully-realized characters. Tobe, on the other hand, is a stock or two-dimensional character.
Throughout the story, we never see Tobe other than as a minor agent of minor action--that is, opening doors for visitors, working in Miss Emily's kitchen, running errands, and we hear him only once or twice. There is little for us on which to base any kind of judgment about Tobe because he we are never privy to his thoughts, except by implication, and his entire role in the story is to carry out perfunctory actions. In other words, nothing he does affects another character or the essential action of the story.
The only time we see something of Tobe's inner self is perhaps when he is described as opening the door for the visitors to the funeral and then quickly leaving the house through the back door, never to be seen again. Obviously, he knew what the town was going to find upstairs and didn't want to stay there for explanations.