Sixtus Quin--what is his role in life?

What exactly is Sixtus Qin, a Storm Commando, SpecNav trooper, or what?

 

mAccording to CUSWE, he was Special Forces:

"Quin, Sixtus
this huge, dark-skinned human was a member of the Imperial Special Forces unit under the command of Marl Semtin. During the search for the Eidolon, Sixtus and his team were sent to Ryloth to intercept Rogue Squadron before they could recover Firith Olan. Sixtus and fellow agent Septaas were pitted against Wedge Antilles abd Winter by Cazne'Olan in a virtual-reality battle to determine who would obtain Firith. Sixtus and Septaas defeated the Rogues, but all four were swept away in a firestorm. When he learned that Semtin had taken Firith off Ryloth himself, Sixtus became suspicious of Semtin's loyalties. When he discovered Semtin at Eidolon Base trying to build his own empire, Sixtus executed Semtin and - along with his entire unit - defected to the New Republic. He joined a team of infiltrators, led by former Rogue Elscol Loro, and specialized in the liberation of worlds from the ground. One of the most notable worlds Sixtus and his team liberated was Thyferra. Working with Rogue Squadron - which had resigned its New Republic commission - they managed to obtain help from the native Vratix and took control of the bacta production. (XWBT, BW)"

However, A Guide to the Star Wars Universe (3rd edition) also says he was a 'former Special Intelligence operative" for the Empire who defected to the Rebels after betrayal by his commander.

 

He fought for truth, justice, and the Aust way.

And boy did he look huge in Battleground Tatooine.