perhaps he is of mixed blood, i believe if his father was nord and mother redguard(or vice versa), he would be allowed in so long as he believed as the nords do. funny thing, i thought he looked more like a black guy than a redguard when hes naked, you know EBONY warrior. still dont think he would not be allowed into sovngarde just because hes not 100% nord.
Pretty sure anyone whos beleif is in Sovrenguard will go there ( to face Tsun) if you have earnt it. After all Tsun makes no distinction between Nord, Agronian, fifthly Thalmor or cheezeburger cat.
Just up front is "the special hall" for the Nords that think they were the only ones to get there. A little further in is "the real mead hall" where the party is rocking.