Don't know the guy and not trying to defend him, but I don't think that was the issue.

I think what happened was there were enough volunteers senior to him that by the time it came to his request the pilot that he would have been "replacing" on the displacement list didn't have the seniority to hold EWR 756 CAP, so his volunteer bid couldn't be awarded. I am guessing that is the only request he had on his Displacement bid, so since he couldn't get the EWR 756 Captain, he wasn't awarded a voluntary Displacement.