From Mr. Young's en banc brief, "If Defendants rely on the concealed carry permit as an alternative to open carry, then that concealed carry permit process must comply with Young’s due process rights."
The Defendants did not rely on concealed carry as an alternative.
Given the three-judge panel decision in conjunction with the Appellants' Opening Brief, plus the en banc petition, the only way that concealed carry could have been relevant to the en banc court depended on Mr. Young filing an en banc petition seeking concealed carry. He didn't.
And even if he had, en banc panels are reluctant to overturn prior en banc panel decisions unless the prior precedent prevents them from adopting a legal rule in the case. The prior en banc precedent is, of course, Peruta v. San Diego.