Six months was a considerably long time for the absence from the Imperial Phoenix Military Academy for the regular students. Yet for the members of the Special Course Class, it really wasn't due to their privilege.
Many members of the Special Course Class needed to take a long absence from the Academy for one reason or another. For that reason, Headmaster Kane was often taking prolonged leave from the Academy.
Most people who were in the Special Course Class had their specific needs, some had other duties within the Imperium, some had to attend very specialized forms of training that couldn't be carried out at the Academy, and some had other things to do that were deemed necessary enough to grant them a set of privileges.
Soon enough, all three of them received their absence leaves signed personally by the Headmaster Nathril El-Amini Kane, and they departed from the office of the Headmaster of the Imperial Phoenix Military Academy.