The liberal narrative is that Jamie Foxx wouldn't be a racist because he's a "person of color", high on the diversity totem pole, second only to LGBTs on the diversity totem pole. They would also argue that a black person can never be racist because they're not part of the "white establishment". They would praise him for being black and proud. If he'd worn a dress while he made this speech, he would have been even more esteemed.
It's interesting the article specifically points out that conservatives called him racist. This is because conservatives define racist differently. Liberals define racist as "white person" or , "people who do something that liberals don't like are racists". The latter definition of racist can even apply to non-whites such as Zimmerman.
Anyway conservatives define racist as "having malice toward another person or a group of people based on their physical race".
That's why it's only conservatives that are calling Jamie Foxx racist. Jamie Foxx is neither white nor conservative, and he's not doing anything that liberals don't like, so he therefore can't be racist to liberals.
To liberals, unless the black person is a conservative, a black can never be "racist", they can only be "homophobic".