So long as the definition of one excludes some members of the other, no matter how large the subset, they are not synonymous
Agreed.
While the legislative definition does this, the constitutional meaning does not exclude anyone. TCase-by-case circumstances might render specific individuals unsuitable for being called forth under the militia clauses, but they are excluded by executive or judicial action, and not by definition. The constitutional meaning does not exclude anyone.
Under the constitutional meaning, the most heinous criminal in death row is still a member of the militia, and can theoretically be called forth, even though no executive officer would ever allow him to serve such a purpose. He is not deprived of the right to keep and bear arms due to not being in the militia. He is “deprived of life, liberty, or property”, including RKBA, through “due process” in accordance with the 5th amendment.