They say that you must "present" as a black woman. If you have to TELL people you have black ancestry, then you benefit from white privilege. Youre assumed to be white unless you say otherwise.
Its the difference between someone like Halsey or logic and Barack Obama or J.cole . Obama clearly looks like a black man and is treated that way. Halsey looks like a white woman with a slight tan. There are experiences that an Obama or J.cole looking mixed person will have that a Halsey or logic type won't. It's not fair but that's the system we live in and until white people change their behavior, we should create spaces for people who have the black experience and protect those spaces from being watered down.
If a light skinned mixed person that looks white wants to be in a space full of people that don't have the same life experience and she's told she isn't allowed in, if she truly is connected to the black experience she'd understand why she isn't being let in and just move on.
Instead she's crashing out exactly how a white person might. "The rappers say it why can't I?" Type energy.
I've always said that biracial/mixed individuals, more often than not, can have split personalities, a Black side and a white one. It might sound silly, but I believe that to be true. As you said she's crashing out the same way a white person would when Black people exclude them from something.
A faux sense of entitlement is the whiteness in her showing; just imagine when she gets upset with the type of attitude she displays, and then on top of that, she calls herself Becky. Not too many Black women out here refer to themselves as Becky.
This woman probably hangs around 70-80% cacs but occasionally tries to latch on to Black people when it's convenient, and this is why mixed/biracial individuals, not all of them of course, but a lot of them, can be a mixed bag on where they stand in terms of their Blackness.