فَلِإِفَادَةِ عَدَمِهِمَا
Using a noun for the predicate avoids those two features: a specific tense-marked event and the implication of repeated renewal associated with the verbal form.
A nominal predicate often foregrounds the established character or continuance of a quality. This does not prove eternal persistence in every context; the situation still controls interpretation. «زَيْدٌ كَرِيمٌ» presents generosity as Zayd's quality rather than reporting one discrete act at a particular moment.
Accordingly, a noun can suit a stable characterization, while a verb suits the reporting of an event and its temporal orientation.