Like so much else in Lee's film, there is no easy answer here. On one hand, diversity is a source of strength in the restaurant as it helps to make Sal's a part of the neighborhood. In a particularly poignant moment between Pino and Sal, he tells his son that he reveres the fact that his pizzeria has been in the neighborhood for so long. The fact that the neighborhood kids eat his food and have consumed his food for so long is a source of pride for him and a representation of the strength of diversity present. Another instance where diversity possesses strength is the bond between Mookie and Vito, where a man of color and a White man can share a positive relationship. To an even larger extent, diversity can be seen in Pino's love of celebrity. Pino loves "Magic, Eddie, and Prince," and this is a reflection of diversity, albeit on a much smaller level.
Yet, diversity might not be present in terms of diversity of thought. The sequence where each member of an ethnic group spouts off the cultural stereotype of another is a reflection of how diversity can prove to be challenging. Another instance of this would be Buggin' Out's fundamental criticism of Sal's. While he might have taken his claims to a bizarrely intense level, the base has some merit. Since most of Sal's customers are people of color, it might be more representative to have "brothers on the wall." It is a moment where diversity proves to be challenging. Finally, Mookie's throwing the garbage can, precipitated by Sal's misapplication of anger towards Radio Raheem's radio, and the intensity of seeing one of their own killed at the hands of police officers creates a tableau where diversity can cause challenges, if not understood properly and if not revered in an appropriate light.