I'm gonna say it's not Mitchell. Mitchell was like some sort of Dark Phoenix mutant with his mind powers in TOS. This seems more calculated madness. Revenge plot against those who Benedict's character feels wronged him. Garth of Izar the former Star Fleet Captain who lost his mind and was sent to a prison ALL THE WAY BABY!
It's possible he used the same scheme he tried using on Kirk back in the Prime Timeline Whom The Gods Destroy', but this time he used it on a less intelligent captain who didn't think to password protect his ship before taking commands to beam up anyone from the planet's service. "Queen to Queen's Level 3"