Responses
Why do they have to kill him cause hes a doctor
the emperor was disfigured by a doctor in someone's attempt (forgot who in the royal court) to usurp the throne. The rebellion didn't succeed, the emperor had all doctors executed. Choa is also the son of the doctor who disfigured the emperor, so that's double trouble for Choa since #1 he's a doctor and #2 he's the son of the doctor who disfigured the emperor.
Choa is too trusting... what if Baeglang wants Mujin dead? He could have also been executed for admitting he's a doctor.
Good thing Baeglang didn't kill him... but we'll never know what Baeglang does in the future.