Kids are very aware of how social media works. It's naive to think otherwise. Comment or not, she made it public the minute she hit send.
Don't get me wrong, I'm not excusing the behavior of the press here or saying that her outing herself excuses what they're doing in the wake of it.
I'm just saying that to assume she had no idea what she was doing here is a stretch too far. It might have gone down differently than she intended but she knew she just made it public. Kids aren't idiots and they grew up with it. She knew.