General Discussion

Even now, having read some of the coverage, I still don't know how much risk there actually was after Allen breached the security point and was stopped.

It sounded from some people there that this was on a different floor, there was more security on the stairs going down to the ball room and then more security before the actual entrance to the ballroom. They also kept everyone not in the cabinet in the ballroom. That suggests they deemed that was some safety within that room as opposed to moving all of them out.

This does not in any way excuse Allen and in the moment they had to consider that others could have been involved. Could the evacuation have come because they considered that there could have been other means through which another assassin could get to the ballroom? It would seem to be the SS job to insure that ALL entrances to the ballroom including from the kitchen were secure. (Likely requiring the kitchen itself to be secure.)

Even though the actual risk to the President at the point when he was evacuated may not have been higher than the risk when people passed into the secure area in the White House in previous administrations. However, it might be a good time to assess SS procedures used in non WH Presidential visits.