I agree. What you say about avihimsā is an appropriate way to regards the environment from the point of view of the Dhamma.
The efficacy of the Dhamma is measured in terms of internal mental purity, with respect to the objective ideal of nibbana.
The efficacy of environmentalism is measured in external environmental purity, with respect to a subjective ideal of a utopian environment.
Avihimsā contributes directly to internal mental purity.