Im VERY confused by that image, VERY confused. Let me explain:
When a woman wants to showcase her bum, and just her bum, she does it by showing her turned to the back with legs toguether or slightly crossed, that is the angle that showcase the best booty shape. That for a woman is SENSUAL and NOT SEXUAL (I know men dont do that difference but for women is night and day), so other women should NOT shame her.
BUT, she did with spread legs, and that for a woman is very concious and aware that is no longer about the ass, but about her cunt, which takes the protagonist role then, and that is no longer SENSUAL, it is VERY SEXUAL. Other women, will shame her for that, that is unaceptable behaviour. That is cheap bitch status woman in the intrasexual competition (I know I know this has no meaning for men).
At the end of Gayshawn episode, she calls herself in her inner thoughts cheater. At the end of the old guys episode, one of them shames her for doing sexual things with other man while she is married and she didnt denied, or excuse, or justify, or fight the though, she just moves forward instantly, and that means that her self image is of a cheater. Sophia considers herself a cheater.
But there is a difference between being a cheater at random moments, just mere situations or accidents, than proactively become sexual in public with a bunch of kids she doesnt know about and their parents she dont know are present a few meters away.
That scene, even if its subtle, means there is a HUGE transformation inside of Sophia. I mean HUGE. At that point, she could be riding dicks all day. Most of the "oh my god what am I doing!" is stupid text, she is FAR past that point if she is spreading her legs infront of everyone for them to see her cunt.