Lesson learned
Sometimes, kids can be unreasonable and think that the entire world revolves around them. In this case, it makes sense that a school would not bend over backward to accommodate just one individual. But when that kid has a good argument and a rational thing to say, we need to listen.
After all, we want to make sure that they are comfortable in school and feel relaxed and not trying to survive a heat wave. It can be unbearably hot nowadays as well, so shorts would really make a huge difference as opposed to bulky pants. How would you feel if you had to wear that in the heat?