Throughout the history of the text, the printed editions of the Book of Mormon have varied regarding the question of whether god should be capitalized when referring to a god other than the true God:
In each instance, the critical text will follow the standard practice of not capitalizing god when it refers to a false god. Nonetheless, some of these examples are rather complex, and therefore each one will be considered on its own grounds. Here in 2 Nephi 9:30, the word god refers to treasure, not to the true God; thus the decision of the editors of the 1981 LDS edition to remove the capitalization is appropriate.
Summary: Maintain in 2 Nephi 9:30 the lowercase god of the 1981 LDS edition; the god referred to here is treasure rather than the true God.