It's not all that important what the main website says; compared to the game, novel, etcetera, it's a secondary source at best.
In TFU 1, I believe that from the point when Vader found him, he consulted the emperor about the boy and they decided to use him to find the rebels. The first time Vader Betrays SK when he stuck a lightsaber through his body, I thought that was just an act put on by Vader and Palp to sell the deception.
This I can't buy. If Vader hadn't ended up faking the apprentice's death on the Executor
, he could have been sent on the mission to find the rebels and he would never have questioned the assignment like he did (Vader's betrayal was one of the main things that made the apprentice reconsider his motivations and goals).