Ahh, bringing up 'constitution'? Sure, nothing written in the Constitution of Pakistan about any 'Red Zone' but I am sure there is something about providing 'security' to the state institutions and to the diplomatic staff. Even if there were none like that the Red Zone holds many important seats of power and diplomatic staff; one attack, say, on the Embassy of USA or Switzerland, would put Pakistan on the map even higher.
But why bother with such mundane considerations? The target was always to cripple the state of Pakistan! Our fake Lenin and Mao (Qadri actually quoted them) wanted a revolution. After all, thousands of Lathi bearing, foaming at the mouth, desperate mobs could be entertained on the Rose Garden Lawns of the White House?
BTW, after the attacks happened, as if, on a cue, the supporters of the thugs in this very forum came up with excuses like 'Oh, so buildings are more important than the lives'.
"Uzr e Gunha, Bud tur az Gunha" (Excuses for sins are worse then the sins).