Mission creep.People want something, or someone, to blame. This will be yet another case study of the normalization of risk and I'd put money on this being a multitude of things that finally came together to form the perfect storm.
I believe Reagan could close with minimal impact, but it's open because it's convenient for Congress flying home every weekend.
Maybe reduce the number of flights in/out.
Killing chopper routes through the airport will probably happen.