I guess this is another difference between Fed and NCAA. In NCAA rules, all penalties can be declined and an illegal pass does not result in the play being blown dead.
In NCAA rules, if a player is flagged for an illegal pass, the other team has a right to decline the penalty. In the scenario listed above, under NCAA rules, the defense can accept the penalty resulting in a safety or decline the penalty and take the ball on the loss of downs.
I do not know Fed rules....so maybe Redding applied the NCAA rules on mistake???