Why does nominative «قَيَّارٌ» in the poem need grammatical explanation?

Conditions of the Predicate: Ellipsis, Reconstruction and Expression

• Because inna governs an accusative-position noun, but Qiyār is nominative
• Because Qiyār is itself the nominative predicate of inna
• Because every noun before the emphatic lām must be accusative
• Because coordinating a nominative after wāw is always licit