What was the inspiration for the name?
I assume it wasn't The Greater East Asia Co-Prosperity Sphere, better known as The Empire of Japan in World War II, since you wouldn't want to pick a name associated with massive human rights abuses.
By the time such a group gets referred to as a 'diaspora' in this sense, it is often to emphasize the continuity-of-tradition-and-vibrancy in a new place, and thus mostly positive in its connotations.