osage10,
In principle, it is possible to get two hardship waivers (14.2.5), and then he might be granted a waiver to the 10/15 semester/quarter limit (14.2.2.4). If the school is successful in obtaining all three waivers, then he could pitch in his 6th year of college.
I looked up your son's pitching record for 2013. He pitched in 5 games, 3 of which were in the last week of the season. Based on the letter of 14.2.5, it isn't obvious how he would qualify for a waiver for the 2013 season. He clearly wasn't "incapacitated", especially given his excellent ERA. All of the games occurred after he had seen a doctor (who didn't find a reason to shut him down).
Of course, it doesn't hurt to try for the waiver.