حكمه: وجوب العمل بمدلوله قطعاً مع احتمال النسخ في زمان الوحي.
The ruling of mufassar is to act decisively upon its indicated meaning, while the possibility of abrogation may still have existed during the period of revelation.
Definitive indication here results from the speaker's clarification. Naskh is a separate category: a later authoritative revelation superseding an earlier legal ruling.
The textbook does not claim that the angels' verse was abrogated, or that every mufassar text has been abrogated. It states the general theoretical possibility of naskh at this grade during revelation.