وإن كان المخاطب مترددا في الحكم طالبا له
If the addressee hesitates about the judgment and seeks its resolution.
Such a listener has considered two possibilities: did the relation obtain or not? They are not merely hearing a topic for the first time; they want a decision.
If a listener has received conflicting indications of Zayd’s arrival, «إِنَّ زَيْدًا قَدْ جَاءَ» may be more fitting than a bare «جَاءَ زَيْدٌ». The reinforcement addresses a real question.
Here emphasis primarily helps resolve hesitation, not overcome settled opposition.