I used it as a catch-all phrase for whatever most people would consider a reasonable exemption from prohibition, and used it to avoid a prolonged derailment of the post's point.

Most people would agree that possession of nuclear weapons should be prohibited. Insofar as other sovereign governments do have them and threaten to use them, and insofar as on rare occasion their use may arguably save more lives than non-use, most people would also agree their government may be exempted from an otherwise universal prohibition on possession of nuclear weapons. Hence the purpose of using the subject as a "code phrase" to make a point without getting derailed. Seemed an obvious, simple, and understandable literary tool at the time.

Yes, the issue is somewhat moot as, until recently, nuclear weapons were something only governments had the resources to construct, maintain, and deliver. That civilian ownership is night unto impossible should have been obviously irrelevant to the point being made. That private manufacture IS becoming viable for the ultra rich (legal and societal prohibitions aside) makes the "but only governments are capable" point moot in turn.

If I presented my personal views on individual civilian possession of nuclear weapons, a flame war would ensue with a great many impassioned respondents failing to hold any interest in understanding my view.