[quote=@Primal Conundrum]
Only objection I could think of is that he looks more qualified than our actual captain to be in charge with the military history to back it up, so it wouldn't really make sense that he was assigned to work under Soloman.
[/quote]

While definitely experienced, Grayeson's military history is on Earth, with the marines. He would need experience on spaceships to even come near the qualification for captain.