ʿAlamiyya describes the word’s use as a proper name; waṣf describes an adjective in use.
أَحْمَرُ (“red”) is adjectival, while أَحْمَدُ used as someone’s name is proper. Either may also have a verb-like morphological pattern, but proper-name status + adjectival status are not counted as two coexisting causes in one use.
This explains the book’s restriction: «مَعَ غَيْرِ الْوَصْفِ».