I take it as a sign that she doesn't care all that much about ratings. Again, if you ever start to see her ratings tank - as in drop off drastically - then she may be obliged to invite guests on to her show with whom she disagrees. Until that happens, she can invite anyone on to her show that she feels like.

Besides, just because someone is a woman doesn't mean she's automatically going to get an invite to the show, VP nominee or not. To suggest as much could be construed as sexist.