The expression al-munazzal ‘ala Rasul Allah ﷺ identifies the Qur’an as revelation given to the Messenger ﷺ. It is not merely the personal authorship or scholarly opinion of an individual.
A scholar may write an explanation of a verse, and that explanation may be useful. Yet a commentary is not itself the revealed Qur’anic text. Distinguishing revelation from human explanation of revelation is essential when evaluating the authority of legal evidence.