The other students were already standing.That's ridiculous, and like Damo, you have to make up a reason for the order in spite of the all-too obvious that he was ordered to stand for the flag, not other students.
Was he talking while they were reciting the pledge?
He was "ordered" to stand up to show respect for the others who stand for the pledge. Just as your mother would have grabbed you by the ear and stood you up for a prayer at a place where they stand for that. Even if you didn't pray.
The focus on the flag by the left is a sign that they are, in this case, being deliberately obtuse and pretending that signs of respect for others can only be construed in one way. Funny, it is usually the conservatives who we are told cannot see "shades of gray".