I think the argument she is trying to make is that the Williams sisters don't have to compete against men in Tennis, at least not directly. Women's Tennis isn't necessarily "male dominated". Again, it's a bad way to try to make a point about the systemic sexism in Hollywood.
I think, and this is the last I'll say on it, that what makes this point all the worse (on top of seemingly attacking two of the most prolific black athletes in the world), in that making movies shouldn't be a "competition". Tennis is. Sports are about winning. Film making should be more about artistic expression, which is why, like I say, she should have kept her analogies to Hollywood, as Sports and Film Making are not very equivilant endeavors in my mind.
I would almost agree...problem is lots of the trials/tribulations the sisters faced over the decades had nothing to do with their on court competing vs women. The male gaze was heavy across the board to critiquing their attitudes, their gameplay styles, to their looks
As a casual fan of Tennis I can remember shit like:
"Who are these manly women unfair whupping on these other female competitors, PED's? Their bodies are unnatural, unwoman-like"
"It's a bit too much, I get the Nike endorsement deal, I get these are the same clothes other female competitors wear but it's a bit too much body; it's pornographic!"
"Why is Serena throwing a hissyfit? I know it's like a D- tier McEnroe rant at best, but still it's a stain on the sport"
And that's just shit I see I can write off as just misogynstic driven by male media, I won't even dip into the blatantly racist shit, lol.