Trouble distinguishing STO vs STS

[anagogy]

To reiterate the question: if all are one, is not any action benefiting another ultimately self-serving, and likewise, is not any action that is selfish inherently benefiting all, based on the Law of One? To restate another way: in realization of the Law of One, how can there be a distinction between STO vs STS?

Ultimately, there is no distinction in the sense you mean it. And the polarity of a given action cannot be ascertained by outward physical observation alone. Any action could be STO or STS. It is the driving intent which determines the polarity.

From another perspective, the distinction between polarities is that, spiritually speaking, STO are trying to see past the illusion and see the truth of oneness. STS, on the other hand, seek this same power of discernment but only to control or make the illusory configuration a more desirable one. It is the path of connection versus the path of separation. One exalts the All-self, and the other exalts the separated ego.