Can my son's college discriminate against a son for absences due to illness?

My son had an issue with his college freshman chemistry class whereby the professor would not acknowledge his 3 absences due to illness. The professor deducted 6 points off his final grade because of it. As per the course syllabus, the absence policy does not accommodate students with illnesses as it clearly states “you must speak to the professor beforehand in his office to approve any absence”. It is not practical to expect a student to predict an absence due to illness, and expect the student to show up in the professor's office when the student cannot show up in his class due to illness. To add to this, my son has a documented chronic illness. I didn't see a Category below for civil law.