Ram Jakhu says that the purpose of the Outer Space Treaty is that "there shouldn't be private property in space". So he's claiming a treaty signed at the height of the Cold War established communism in outer space in perpetuity. Hmm.
Even if he's right, which I very strongly doubt, it's a terrible idea. Communism hasn't worked on Earth and is no more likely to work off-Earth.
The environmental arguments are even worse: they assume all human modification of the environment is inherently wrong. That makes sense to the anti-human wing of environmentalism, which is strong in academia, but not to people who value human flourishing more than hypothetical exo-bacteria (i.e. almost everyone).