Do you understand how ATC works? (Please don't take that as condescending) Washington Center is basically a small office in Leesburg, VA full of computer/radar screens and the people that operate them. That one building is responsible for civilian radar coverage in most of VA, MD, WV, DE, and parts of NC, PA and NJ.

So if they have to clear out to disinfect it, that's going to leave a sizable chunk of the East Coast w/o radar coverage. The easiest and safest thing for them to do is re-route traffic to other Area Control Centers for a couple hours until they're done cleaning.