In ME1, during most of the talks, nothing changes. You say the same things with a different tone, but the result is the same.
It´s surprising that in many cases shepard can´t even think of arresting certain individuals. If he tried and the person decided to shoot or commit suicide, it would seem somewhat satisfactory.
In several cases it was irresponsible not to take certain individuals into custody even if it was just to better question them, clarify a few things, obtain recorded statements, place them under observation for indoctrination, etc. Total lack of prudence being displayed.
And to be frank, why am I able to shoot the salarian who wants to scan the keepers as well as Fist, and not kill them, but I always end up having Saleon or ALL of the exogeni people killed? Can´t I thrown some of the several spare granades that I used on Feros to merely incapacitate people and that I happen to have with me, equipped, at this very moment?
My people are professionals, using heavy armor and armed to their teeth. Why can´t we simply shoot at their legs after hitting them with stasis, or lift? Is it so hard to capture the exogeni head scientist?
If it was really me, I would leave my 2 squad-mates on that room, and ask the woman who commanded the facility to go have a private talk with me on the other room. I´m sure we could reach some sort of agreement, like having her make a full confession in exchange for a pardon for her and keeping her name secret from the public.