"liberals" are not racist (for the most part). Liberals who worship Beyoncé (and a lot of them are black themselves) do it because they agree with her ideals which she heavily draws inspiration from.
Racist (mostly gays) who almost exclusively stan white popstars often like Rihanna for the aforementioned reasons. Not that hard to understand.
Beyonce was the most non-threatening black artist in the industry, she was basically white. It was just this year that she "embraced her blackness" just because it was the trendy thing to do and society/media was into it.