Wasn't that unintentional?
You have to keep your arms to your side as well, it's not just whether a handball is intentional or not.
It looked like it hit her trailing hand which was bent at the elbow and away from her body rather than right against her side which is why the ref called it. She blocked the ball with her hand rather than with her body so it looks like the right call. Usually you cup your balls and turn your face to the side so the ball doesn't break your nose, this way there's no confusion... though I guess in this case it's cup your cooter