Does the yeshiva have a policy forbidding other sorts of non-emergency medical care during business hours? This is no different.
There are also legal issues if the yeshiva is in the United States. Many emotional conditions are covered by the Americans with Disabilities Act. Schools and workplaces are required to make accommodations for students and employees. If the restrictions are unreasonable or pose an undue hardship on the boy the yeshiva may be exposed to legal troubles.