Neutrality?

Books on community interpreting are full of the neutrality warning. You are just but a linguist, at best, a cultural agent. Only, it doesn't work when I vaguely think I should tell the client I am nothing but your Japanese mouth when I bring you to the police headquarter meet your son, juvenile, who dreamed about Japan while being in Japan and foolishly ended up behind the bar. The father wants to rely on someone's shoulder - BGM : That's what friends are for - asks me if I am available for lunch, wants to be reassured (the lawyer was cold), wants a shot in the arm of vitamin, a gentle slap on the back - BGM : We'll meet again. What machine are you that would slap him back in the face "Sorry dude, i am only but your voice in Japan. Otherwise, I am mute and neutral like a piece of soap". Who would dare behave like that?