I understand the AD's sentiment and agree that he should have written this to stand up for his team. Good for him. I also empathize with the FSU team. They did everything that was asked of them. Tough to be the odd man out.
I disagree with the AD that the selection somehow damages the credibility of the CFP institution. In the current version of the CFP there is no hard line about who gets in. The only criteria that has been emphasized above other factors is winning a conference championship. But even that emphasis has never meant that e.g. an 8-4 PAC champion will be chosen over say a 10-1 Georgia. The selection is and always has been subjective. It's just extremely disappointing for the FSU team and fans that this year there were 5 worthy conference champions and only 4 spots. That's a tough pill to swallow.
Before ya'll slay me, let me add this: The wonderful thing about the proposed(?) upcoming 12-team playoff is it incorporates BOTH components: P4 Conference champions are in AND there will be enough wildcard spots to include many deserving teams. There will still of course be some controversy around teams maybe teams 9-12. But imho that controversy will only add to the buzz.