It's implied that Ga Bu might be tempered, only kept alive as a special request from Alisae. The circumstances leading to his current mental state are extremely suspect, but it's still ambiguous.

Either way if he is tempered, Alisae's treatment for Sin Eater victims was explained as plausibly being able to cure tempering though some mystical mumbo jumbo, so if that's the case I'd wager she'll try it straightaway.