The fallacy of the "Appeal to Nature" rests in a dualism-- the erroneous notion that humanity is fundamentally separate from nature. This engenders the belief (on which the fallacious appeal depends) that any modification humans make to their environment is prima facie "unnatural"; it also engenders the belief that, as separate from nature, humankind is somehow immune to the consequences of its modifications. To re-introduce humans (and for the theologically inclined, God) into nature (cf., for example, the work of Hans Jonas, or Lovelock and Margulis's Gaia hypothesis) helps us greatly in eliminating this dualism. If we further understand that "nature" is not static, we can deconstruct the fallacy by retaining an inherent value to nature as an (all-inclusive) entity on which we all depend, while simultaneously rendering "unnaturalness" a meaningless category. Rather than judging a phenomenon, action, or concept on whether or not it is "natural", we therefore judge it based on its consequences for the natural system (and/or particular elements thereof) of which we are all part.
Is this tenable?