So, Jim Zub says: No, he's not a villain. HE's just struggling and trying to find balance and that this appearance tees up another one for the Sentry elsewhere in the marvel universe. Most of Marvel's creators are pretty fond of the character. So breathe easy. Moreover, his actual appearance in the first issue of Agents of Wakanda is minimal, but we do see that the Void-demons they struggle against are well handled, and their reaction to the big reveal is pretty great.