Magneto's Reign
Vance was a key player in the reign. Next to Magneto he held the most true power at the time. He augmented Magneto's forces with his allies. All the while hiding his magical capabilities. It's thanks to Vance that Magneto was able to arrange his own death. Most, if not all, of Vance's alliances supported Magneto's reign. To this day the Avengers and X-Men do not know precisely what Magneto's regime did, all they know is Magneto is a supervillain and he ran things therefore his regime is inherently an evil one. His actions as king were ignored because of his status as a villain.
Back To SHIELD
Vance wanted the transition to the new normal to go smoothly so he helped SHIELD catch key players. Among the players were members of Aaron's JBL, Sons of Sabretooth and difficult Brotherhood members. His reward was SHIELD repeatedly knocking him out to run experiments. He went with it, sadistic as their actions were.