The idea of protective services is to reduce and manage risk. The thought that you could eliminate risk through any security system or any amount of training and personel armament is absurd. The attempt to remove weapons from a building is an attempt to make it more difficult for an "evil-doer" to accomplish his aims. If every potential political target were required to be prepared to defend themselves we wouldn't have need for a secret service man to gard senators, congressmen, cabinet members etc. because they would all be wearing side arms as would everyone else who worked for them. In this situation you might be allowed to enter the capitol buildings with whatever was in your pockets and it is reasonably certain that in such a situation there would be fewer individuals who would be silly enough to try something. OTOH, President Lincoln had training, and fire-power and security guards - look how well it protected him - in the good old days.

The issue here is not relative effectiveness of either scenario but rather the abridgement or perceived abridgement of our (americans) rights to walk about armed to the teeth. (something that few if any other countries see as reasonable or legal)

If you are attempting to reduce risk by disarming individuals who you don't trust then you will move in that direction until you are satisfied with the level of risk achieved. This may include body-cavity searches for potential C4 caches at some point. Currently it involves examining whatever makes the metal detector go beep, x-raying things that you don't and occasionally patting down "suspiscious individuals"


[RANT ON]
Given the intelligence of some of our elected officials I am not sure that I want them carrying handguns into the capitol buildings or anywhere else in an effort to secure themselves from attack. Rather have trained individuals who have no political clout simply keeping the peace. Odd how anti-gun activists are happy to have gun toting individuals protect them. That particular pathology cuts accross all political and geographical and time boundaries. Pacifists have always lived peacefully only where others are willing to take up arms to enforce the peace.
[RANT OFF]