While visually aggressive, the "spitting" trope in fiction is a shorthand for exploring themes of power abuse and human dignity. It effectively establishes the stakes of the conflict and defines the moral alignment of the characters involved.
This scene depicts a fictional power dynamic within a fantasy setting, focusing on themes of dominance and submission. All characters are consenting adults engaging in negotiated dynamics.
In the long term, the incident is likely to have significant implications for the royal family and their relationships with their staff. It may lead to changes in the way that the palace operates and the way that members of the royal family interact with those who work for them.