A 4-year-old unvaccinated child presents to the emergency department with a 6-hour history of high fever (39.8°C), severe sore throat, drooling, and muffled "hot potato" voice. On examination, the child is sitting upright, leaning forward on both hands, with inspiratory stridor and mild respiratory distress. The pediatrician suspects acute epiglottitis. The label **D** in the diagram emphasizes a critical management principle. Which of the following best describes the rationale for the approach indicated by **D**?