What does this have to do with HFT? If I had someone (man or machine) managing my money and a credible source had reported two explosions at the White House, and there is some chance it could be true, I would like them to incorporate and react to that information and the likely outcomes as quickly as possible. And then if it turns out to be false, I'd like them to react to that as quickly as possible as well.

Which is exactly what happened. No different to a rumour rippling around an old school trading floor and then being discredited. Just faster and more efficient.