I can't be the only person (red state-raised American, even!) to have had serious difficulty reconciling Business, as She is Practiced—including exactly what you mention—with the basic ideas of fairness and justice we're all immersed in from birth. The whole thing, top to bottom, makes me feel pretty icky, and it's only that everyone else acts like it's OK that keeps me operating in ordinary society (which is, I'm pretty sure, a substantial moral failing on my part)
No, by that line of thought things that are legal are not necessarily ethical and vice versa. The weird contrapositive you seem to assume it implies only says something about you, not about the statement you responded to.
Maybe, and certainly unethical and unacceptable are not synonymous, but no that is not where the line of thought leads. It only leads to not accepting dotted i's and crossed t's as the final word.