Your background is good and if you look around is as good or better than those who have been selected in the past several years, that includes your OAR, your degrees and GPA's which are great.
There are some things that make me question what he told you, first he is an Intel officer, Intel officers do not sit boards to select Supply/SWO or any other designators other that IWC. He may have made that comment if people were going for SWO-IP/Oceano at the IWC board. If you were to look at the signed selection results and were to look up those names you would see what I am talking about.
I never say or would have said in the past a person has a great shot at Supply/IWC as those are small designators that can have a lot of applicants, in some cases selection rate has been as low as 10% however in your case if you weren't to be selected I would believe it was whatever this person put on the evaluation sheet that sunk you.