Your OP said he won nationals with one leg. I compared him to someone with no legs who won, only to lose the next year.
Also there is no way that the PSU staff KNEW he was going to beat Griffith during the dual. Nationals came AFTER the duck. They had some good evidence only after hurt Carter beat hurt Griffith.
People DO lose matches. Brooks did lose a match to ISU his 4th year. I don't think Carter was necessarily "afraid," but I do think the staff sometimes makes decisions to minimize any risk to their athlete's seed.