Pretty plausible. Some YouTuber (this one I think: https://www.youtube.com/watch?v=VbJ4ilDvGyc) quite a while ago mentioned how the contractor tasked with the ballroom remodel is predominantly known for building datacenters and SCIFs (Sensitive Compartmented Information Facility).

So, instead of going to a masquerade in a ballroom?

It's presumably a SCIF, masquerading as a ballroom.