I agree..would have been happy with the freeze frame at the end when his 8mins was up.
I can only assume the studio, or whoever wanted a little more upbeat ending. But it then leaves the messy subject of what happened to the guy he replaced He's effectively stolen his body and killed him.
In my head, Sean dies in every other reality anyway, so the only way that Sean's "body" can live on is with Colter in it to save him if that makes any sense. I'm not a sci fi geek though, so I don't know if I'm missing some obvious point.