How should al-Nawawī’s discussion of solitary reports be handled here?

The Meeting Condition in Muʿanʿan Hadith: Muslim’s Rejoinder and Route Comparison

• There was never any disagreement on acting on solitary reports
• Separate practical authority from epistemic certainty, without attributing Nawawī’s analysis to Muslim
• Every solitary report necessarily produces immediate certainty without evaluation
• Muslim personally detailed all juristic disagreements here