My daughter had a class with a similar policy this year. However, students with excused absences were given the opportunity to make up participation points after school on certain days. My daughter had a number of absences for sports and other activities, but she always made sure to schedule a make-up.
I would double check with your child that the teacher did not in fact provide any make-up opportunities. If not, he should pursue the issue with guidance, student dean, or the appropriate chain of command.
I agree with others that it is usually more effective if the student pursues the issue rather than the parent.