Peter, most of the reasons people give for making exceptions are not themselves meta. For most of the examples you give, the intuitive justification is something along the lines of “the reason killing is wrong is that life is valuable, and in these cases not killing would involve valuing life less than killing would.” Nothing meta there.
Aaron, I don’t see how your proposal resolves debate over exceptions. For example, consider abortion. Presumably both sides on the abortion debate agree that life is valuable.
Peter, most of the reasons people give for making exceptions are not themselves meta. For most of the examples you give, the intuitive justification is something along the lines of “the reason killing is wrong is that life is valuable, and in these cases not killing would involve valuing life less than killing would.” Nothing meta there.
Aaron, I don’t see how your proposal resolves debate over exceptions. For example, consider abortion. Presumably both sides on the abortion debate agree that life is valuable.