Principal gave the green light immediately after the Vice-Principal discussed the plan. There was no reason to deny as it seems to carry many benefits to the students.
However, such reasons were not seen by other schools.
They simply took the opportunity to further condemn Ace Academy who was already getting enough criticism from media and people alike for their failure during Devil's Invasion.
They were laughing at Ace Academy's new method of training by saying how inefficient and a waste of time it was. Rather than doing such jobs, they feel that students should focus on ranking up quickly.
Higher the rank, stronger the students. There was no need for other factors when one's rank was higher than the other.