Who Counts as an "Ethnically and Racially Diverse" Jew?

In an article on the appointment of the first-ever black female rabbi in the United States, the Jerusalem Post writes that "[s]he will be the first African-American rabbi to lead a majority white congregation, despite the fact that about 20 percent of the American Jewish community is ethnically and racially diverse, according to the San Francisco-based Institute for Jewish and Community Research."

It's hard to understand what that means. Is it that 20% of American Jews are nonwhite (possible, but unlikely)? Of course American Jews are ethnically (if not always racially) diverse in the sense that they come from many different countries. But how did the Post come up with the 20% figure?

Apparently, the 20% number comes from this study by the Institute for Jewish and Community Research, which found that about 20% of American Jews are "African-American, Asian- American, Latino, Sephardic (of Spanish and Portuguese descent), Middle Eastern, and mixed-race Jews." It's not clear, however, why these groups count as "diverse," while Greek Jews, Hungarian Jews, or Italian Jews others do not. It's not a racial distinction, since many Latino Jews and Sephardic Jews from Spain and Portugal are not darker-skinned than Jews from many other parts of Europe.

The real answer may be that the groups listed as "diverse" in the IJCR study are those (with the possible exception of Sephardic Jews of European descent[update: and possibly also "Middle Eastern" Jews]) who might qualify for preferences under various affirmative action programs; roughly speaking, the groups in question are nonwhite groups that have historically suffered discrimination at the hands of state and federal governments. But even if that definition of "diversity" is the right one for purposes of allocating affirmative action benefits, it makes little sense in the completely different context of trying to analyze the ethnic complexity of the Jewish community.

UPDATE: An alternative explanation is that the IJRC study means to count as "diverse" all non-Ashkenazic Jews. However, most Greek and Italian Jews are non-Ashkenazi, yet they don't seem to be included in the study's "diverse" category. Also, many Asian-American and mixed-race Jews follow Ashkenazic rites, yet they are.