This post is the hammer smashing the nail on the head.
If you care about the overall health of collegiate track and field, you want this rule to remain and to be almost always upheld. It creates incentive to have larger teams, more walk-on opportunities, to get out and race your athletes (and eight meets between indoor and outdoor is not over racing).
Without this rule, teams could slash budgets by having fewer athletes, having fewer of them travel (less hotel rooms, less per diem, etc.), you could focus on a few areas and get rid of event coaches, and so on.
Whether you want this particular athlete to get a waiver on appeal is a separate issue (I hope he gets to run) but the rule is a good one.
How can I try to have it both ways?
If an appeal shows a team competed in 8 meets or more and there was a meet or two in which injuries limited the team to 12 or 13 athletes, I would grant the appeal on the basis that "they tried." That is better, to me, than having an injured 1500 meter runner walk in the 100 meter dash to qualify a 14th athlete in a meet.