The toxicity of Halon is extremely low when applied in normal firefighting quantities and concentrations (as I understand it).
Agreed, when automated systems, such as in Flight Simulator buildings are flooded with copious and excessive quantities to cover the worst fire situation envisaged by the designers, then the threat to life due to decreased oxygen levels obviously increases unless you calmly walk outside the subject building, cancel the sim session and have a cup of coffee. You don't have this luxury in an aircraft fire.
I am a human being first and a pilot second. So I demand the very best solution when my aircraft catches fire and threatens the lives of my passengers and crew.
As far as I am aware, Halon has been proved as the very best extinguishing agent available to mankind at this point in the history of aviation (perhaps the one thing Boeing and Airbus agree upon?).
So if some deluded, or perhaps I should say more diplomatically, misguided soul, seeks to remove the most effective fire extinguishing agent known to mankind in preventing my passengers and crew from suffering a fiery death or the trauma of death from falling to earth from a great height in a structurally damaged aircraft, then I beg to disagree.
You want to get rid of Halon? Then, first of all, show me some agent that is at least as good if not better than Halon for extinguishing fires in aircraft. Then I will be all ears...