If the government knew that were was a bio chemical weapon inside a building WITH the suspect inside
There is no way they would try and evacuate the building
You quarantine the building and keep both the weapon and the suspect contained.
I love you bro but the US government would risk a couple hundred lives in order to keep a bioweapon attack under the radar and keep the suspect contained and caged.
BTW I'm not knocking the actual story of the show. I love the show. I'm just talking about this one part of one episode.

The usa isnt supposed to operate blacksites or secret agents on national soil either. Creative leeway has to be given for some things in a tv show.