Because the boy did leave the house, in defiance of his father’s instructions. That is why both facts are tied together.
Fact #1: The boy attended a fire fighter’s funeral to pay his respects. This would have been (unequivocally) a good thing, except that Fact #1 is tied to fact #2.
Fact #2: The boy defied his father’s instructions about not leaving the home (without asking permission to attend the funeral) in order to attend the funeral.
Again. You’re right. Father right. Son wrong. Great role model for the kid.