If you fly "non-rev," you have to follow "non-rev rules." It means if the policy says: no form fitting leggings or spandex, it means "no form fitting leggings or spandex." In the airline world, this is common knowledge. All employees of EVERY airline knows this as you are briefed of this when hired.  The employee who was using his/her benefit of the buddy pass should have explained this instead of trying to be the "victim." Come on man!