The first point, that there is no being to which natural law could apply, is based in this notion:
No thing can be a mereological sum of other things. A heap of sand, then, is not a thing, for it is nothing but the mereological sum of the grains of sand. Whether the grains of sand are things or not is a more difficult question.It’s actually not a difficult question. The grains themselves are composed of molecules, and the molecules are composed of physically separated items like electrons and protons, each acting according to its own form. However, there is no question of an electron behaving morally. Under Aristotelianism, every electron behaves according to its own form perfectly. There are no imperfect electrons. Since any larger object is the mereological sum of the various subatomic particles, with the apparent unity being the sum of the behaviors of the individual particles, every larger object will act according to the sum of the respective forms. Thus every action is in concord with the mereological sum of the forms, and there is no non-good action. That means all actions are in accord with natural law, rendering it moot.
As for the second point, let's say for the moment biological organisms actually were things, because we allowed certain sums of subatomic things to be things in their own right, and these included biological organisms. Then, it turns out every biological organism is a thing with its own unique form. For example, my form is certainly different than my mother's, since my natural processes have made me male and she was female. My form is also different from my father's since his natural processes made his hair red, and then (opaque) white, while mine has been brown, and is slowly going translucent. So, when people talk about the form of a dog in the general, it turns out there is no such thing. Every dog has its own form, and every person has their own form. Rather, we can talk about common characteristics of dogs, or humans, but no some or subset of these characteristics is the form of a dog, or a human. Natural law claims depend upon the use of something being consistent with its purpose, which purpose is deduced from its form, but since every form is different, there is no barrier for the proper use of the penis on one man being different from the proper use of the penis in another man. Hence, the use of the penis in a homosexual relationship by homosexuals is in fact moral. Actually, since the form changes from person to person, and every person acts according to the processes that make up that person, even child molesters are following the dictates of their forms. Natural law is reduced to acknowledging every action as moral.