Answer:
Because she did not want Boo to be embarrassed to be led across the street by an eighth year old but instead wanted him to look like he was in charge.
Step-by-step explanation:
In chapter 13 of "to kill a mocking bird", when Boo got to his feet, every movement he made was uncertain and he coughed and shaken that he had to sit down again. Scout arranged things so that "if miss crawford was watching from her upstairs window, she would see Arthur Radley escorting her down the sidewalk" because He did not want Boo to be embarrased to be led across the street by an eight year old. Therefore Scout played the role of a gentleman.