Should every government agency have a department to investigate threats towards their employees? Why limit it to just the USPS? Why not give investigative powers to the Agency for Global Media or the Administration for Community Living? Should those employees have to risk the very "real and non-trivial" threats they face?
If this was just some sort of way of detecting bombs or anthrax or something I think most of us could get behind it. This is turning the post office into an investigative crime solving agency and not even strictly for the thing they do (mail delivery).