وَأَمَّا إِفْرَادُهُ أَيْ جَعْلُ الْمُسْنَدِ غَيْرَ جُمْلَةٍ؛ فَلِكَوْنِهِ غَيْرَ سَبَبِيٍّ مَعَ عَدَمِ إِفَادَةِ تَقَوِّي الْحُكْمِ
Making the predicate non-clausal is considered when it is not causally linked and is not intended to strengthen the judgment.
The rule contains two distinct conditions. First, the predicate must not introduce an attribution to a related entity that is then linked to the main subject. Second, the construction must not serve the purpose of strengthening the judgment through an additional predicative relation.
Absence of causal linkage alone does not guarantee singularity. Conversely, a clausal predicate does not automatically prove that rhetorical strengthening is the speaker's intended purpose in every context.