I'm not an expert on Daoism, but as I understand it, Daoism defines "wu wei" in opposition to Confucianism's emphasis on the need to submit to social conventions. Daoist wu wei is about submitting to the natural flow of the universe, to nature's way rather than to anything as flimsy, artificial and hubristic as society's or the ego's.
The Tao Te Ching is famously cryptic, so of course you can find support in it for practically whatever you like, by interpreting its aphorisms. Obviously, Daoism doesn't explicitly advocate for social Darwinism since Daoism long predates the theory of natural selection. My point is that today Daoism lends itself to social conservatism and social Darwinism, because of its back-to-nature standpoint.
The Tao Te Ching is full of analogies to natural processes, which support its general idea that "Man is ruled by Earth. Earth is ruled by Heaven. Heaven is ruled by the Way. The Way is ruled by itself." Contrary to the Confucian and secular humanistic view of cultivating personhood through discipline, the Daoist says, "The world is a sacred vessel that cannot be changed. He who changes it will destroy it. He who seizes it will lose it."