The good folks at SIMUVAC do one thing, and they do it well: create fake or "simulated" evacuations. It's kind of like a fire drill for an entire town instead of one building. Someone rings the bell saying there's been a disaster, and all these dudes in military outfits swoop in and help you evacuate. The funny thing is that after the "airborne toxic event," they start doing these simulations all the time.
Now that would all sound well and good if SIMUVAC only simulated evacuations when there was nothing going on. But when the actual airborne toxic event happens, the government still calls in these same dudes. Why would they invite evacuation simulators to a real disaster? According to one of the SIMUVAC guys, it's because they "thought [they] could use it as a model" (21.375).
So how about that? Instead of using the disaster drill to prepare for a disaster, the SIMUVAC guys are using an actual disaster to practice their imulation tactics. It's all totally reversed. The simulation matters to them more than the real deal. But wait—that's crazy, isn't it?
Well, here's the thing: in the world of Don DeLillo, America no longer has any connection to reality. The difference between reality and a simulation has collapsed, and it's never really possible to know whether you're experiencing reality or a simulation. After all, if those SIMUVAC dudes get you out of harm's way, what's the difference between a simulated evacuation and a real one? For DeLillo, there is no difference because in the modern world, the only way we really know if something's happening is if we see it on TV or hear about it on the radio.