Larian Studios Forums Divinity - Original Sin Divinity - Original Sin - General Bruthor the orc *spoiler*

Release the orc first and take care of the guards, and you can then release the prisoners without a reputation drop.

At least some of the human prisoners are still loyal to the cause, believing they are there due to a misunderstanding, or minor infraction, that can be cleared up if they can just explain themselves to someone in charge.