I could honestly see why the Seret Service might be worried about a giant unsecured hole in the building ...
I could honestly see why the Seret Service might be worried about a giant unsecured hole in the building as a security threat. And I agree the administration should have thought about that before starting demolition. It is possible the SS did not have any say in the destruction.
But a ballroom cannot be the only solution to the security breach.
How about a nice concrete wall closing off the entrance to the rest of the White House? Or a concrete corridor/stair leading to the entrance to the Emergency Bunker. Those could be built quick and temporary while the ballroom plans get fully vetted to the extent of the law. I would think there would be some quick solution to the security breach that does not include a ### thousand square foot eyesore.
But what do I know?