The greater share can be defined as a majority.
If you're just making up bullshit up like you have been, sure. Otherwise, no, it's just a plurality.
https://upload.wikimedia.org/wikipedia/commons/e/ed/Obama_and_Valerie_Jarrett.jpg
And? Unless you think the man next to her with similarly dark skin somehow passes for white, nobody would think she passes for white here.
Oh, a /r/The_Donald user, I see where you've been getting your talking points. In the actual, non-LQ picture, she again does not pass for white.