The return of his powers is more involved than Sean waking up one morning and being fine.

The return of his powers is more involved than Sean waking up one morning and being fine. The Retribution Virus story in Marvel Comics Presents gives him a temporary restoration. Later, the Morlock Healer helps make the recovery last during the Muir Island/Reavers period. That's worth keeping straight because there are appearances where he's using the scream before that later healing. It isn't all one event. The Reavers also make it clear that Muir Island isn't somewhere he can retire from danger. People there need defending, and Sean is back in the middle of it. His return works because the book hasn't needed to replace his personality along with his missing powers. He's still the experienced man who has reasons to care about both the X-Men and the people living away from the team.