What is the legal status of a hostile combatant (*Harbi*) or apostate (*Murtad*) if they accept Islam under threat of death?

Primary text

For a hostile combatant or an apostate, it is permissible to threaten them with death if they do not accept Islam (i.e., 'If you become Muslim, otherwise you will be killed'). If they declare Islam, their Islam is judged valid outwardly. If they die while still under this compulsion, their ruling is that of a Muslim because the compulsion was legitimate (against someone whose life is forfeit), validating their action, similar to a Muslim compelled to pray who does pray.