"Its why Serena Williams is accused of 'really being a man' by people who are racist. (And transphobic)."
Notice:
Slagging off Serena Williams for how she looks is not SEXIST but TRANSPHOBIC.
Not only must women be erased, but in a fantastic patriarchal reversal, when anything bad does happen to us, really it's an issue not for women but for trans people. Somehow.
Also notice: The people who are incredibly horrible about her looks are mainly MEN. Men are the ones who think that saying a woman looks like a man, saying "I don't fancy hers much" is the ultimate insult to a woman because obviously the only purpose to our lives is to look fuckable for the boys.
Interestingly men are nastiest to women they feel threatened by - Serena is an incredible sportswoman - so strong, winning everything she looks at, enormously successful, massive wealth. And shocker she's black, yep insecure little man-boys hate her alright.
The same insecure little man boys would be very very very happy to see Serena get beaten by a TIM, I'd put money on it.
Personally I think she's awesome and I hope that she continues being able to do exactly what she wants and now with a baby as well 
(Is it transphobic to mention that she had a baby?)