Definitely interesting to explore these boundaries.
The people who are against music and cairns in parks are not protecting any natural law. They are protecting their specific terraforming project, a park. It is driven by a purely human concept of "sustainability" and cannot possibly be something that existed in a world without humans.
Now, that is a nice terraforming project they are protecting (notice how "nice" is another human concept?) We also tend to spend a lot of energy protecting species that trigger the same neural pathways in our brains as human babies, even if the species would most likely go extinct without our intervention (pandas).
What environmentalism actually does is act as a brake on our other terraforming projects, allowing us to go on terraforming longer and not turn our environment into something inhospitable. But even that is entirely anthropocentric.