You Are Welcome Here, Friend
The closest official Disney guideline to this action would be the rule “Engaging in any unsafe act or other act that may impede the operation of the Disneyland Resort or any part thereof.” Looking at this picture, we can assume she was not impeding any operation due to her handstand gymnastic skills.
Maybe she was training to become an entertainer, or she was just stretching out to make the most of every ride and experience in Disneyland. Handstands help the body’s core, improve balance, and increase circulation. Truly a worthwhile physical activity before engaging in bewildering rides and taking photos of magical scenes.