Of course it's a threat. Civilians doing that would be bad. But governments do much the same via military intervention on a regular basis, hence Yudkowsky talking about airstrikes that one time.

I'm not suggesting to do that, I'm just showing that it's incredibly possible. You could also go with "Tomorrow a massive storm strikes the Netherlands and huge earthquakes striking Taiwan and the US Westcoast", if you have emotional objections to my first example.