I've yet to see how such an option can be done that doesn't either A) force certain character types into being killed (ala DA:O), or B) make it obvious that they're just commiting suicide and their death serves no purpose.
Not if its properly explained that they will die if they go out there and that Martin wishes to handle it alone. If they want to live, it'll be clear that they have to sit this one out. Besides, Martin would act such a way anyway. He's tell you it would be crazy to go out there, and that he wishes to handle it alone. We're all ready considered a hero when we just sit back, only those who were ready to die would go outside. A heroic person wouldn't go because Martin all ready said he was on it, and that they should just stay back an watch. I think it would work well enough.
Possibly working in a second dialoge line from my past example where the hero would ask if Martin is absolutly sure he can handle it on his own, and Martin being truely adimate about him being able to do it would give a hero type enough reason to stand back I think.