What the hell was the purpose of the flower?
Although the powder was later identified as wheat flour, the threatening intent was clear.
"we are gonna bake bread" is that the threat?
"This could have been anthrax or something else deadly" is the threat.
Unless the intent is "this could have been cocaine", in which case the sender obviously wants to party hard with the Ministry of Defense.
I remember a novel in which a hardcore cocaine user is killed by some hippies by shoving his face into a bag full of powdered laundry soap, or something along those lines (it's a really weird story). Maybe that was the intent? Pretend it's cocaine, only to be surprise!toxic chemical?