Why didn't Henry explain why he was late?

Henry was late because he was being taunted by his classmates, the classmates who were on flag duty. Chaz and Denny were making derogatory remarks about Henry's race (Henry was not Japanese). Henry made no repsonse when he was reprimanded for being tardy because he wasn't the types to make waves....... and I believe he thought standing up to Chaz was worth the hour of detention.