Your confusion is understandable. The way the terms "moral" and "ethical" are thrown around is sloppy in most vernacular. Generally, ethics refers to system-wide morality. E.g., I may feel that personal morality compels me to offer lower rates to clients, even though a higher rate may be acceptable under legal ethics. I tried to make that distinction clear in my post ("moral principle in any system") but perhaps I didn't do a good enough job.

The original poster was not referring to individual moral feelings, but to formal ethical systems subject to systematized logical thinking: "classic example of an ethically unsound argument."

There is no religious tradition, no system of ethics, no school of thought in moral philosophy, that is consistent with that position. The closest you might come is Aristotelian virtue ethics. But it would be a really strained reading that would result in the position that opting out of commons mismanagement is required. Aristotle specifically said that being a fool is not a virtue. If anything, a virtue ethics lens would compel someone to try to establish formal community rules to prevent the tragedy of the commons.