You were mistaken when you wrote "This perplexes Lora so much that, while pouting, she tells Annie this is a “real problem”—nothing like Sarah Jane running away from her heritage. (A line that earned the black and white audience’s biggest laugh.)"
She said Sarah Jane's problem was real, she couldn't figure out what problem Susie had. After she said that, it was revealed that Susie loves Steve.
Also, while I thought the movie was good, I do not see how it convinces anyone to vote for Obama. Is that just because Obama is a mulatto, similar to Sarah Jane, except that he accepts his black heritage? While I respect him as a person, I will never vote on someone just because of their skin color. Issues matter, not biology.