My first thought was that it was done to take a swipe at the types that would be showing up for the Solstice celebration that claim that it's all about spiritual connection with nature but turn it into a rave full of upper middle class anglo influencer types in the same vein as burning man.

Any reporting on stories of activist vandalism tend to downplay the fact that it's never permanent damage by design. The reporting always present the story like the fact that the soup or whatever never made it past the protective glass as incompetence on part of the protestors, and not in fact a conscious choice since the goal was never to permanently damage the art.