He is employed by the Holland Group, which provides staffing for our substitute teachers, ... He apparently used some inappropriate language and called a student 'heathen.'
Any time an adult is in a teaching role, they're held to a higher standard. Obviously, Holland thought that wasn't an appropriate way for one of their employees to be acting in school.
It was the second time he had done something like that, and Holland decided he can't be a substitute any more. They can find something else for him to do, but not that.