Also, a static page can be served by many load balancers, if the servers behind them are all unavailable. Standard procedure. In addition, if they had left the sites up during the shutdown, and they had been compromised, how many people do you think would have been infected by an unpatched 0-day left on a government site or 3 for 21 days or more? How many people do you even think would have thought before clicking "OK" to accept something? With no sysadmins to watch logs, catch intrusions and patch software, it's much better to just shut it down.