What's the theory here, other than two things occurring on the same day? By knocking out Facebook.... Haley gets an advantage? If anything, foreign interference would be Russians helping Trump, and he doesn't seem to need help now given that the GOP voters seem firmly in his pocket.
Stochastic terrorisim. Get people afraid because “things don’t work right”. Cause fear and doubt about life in general and have it associated with the election.
So we shouldn't hire interns around the elections or during one. Because the mistakes they create is common cause of these events that some will describe as stochastic terrorism.
Not to say that this would be one. It just these theories usually jumb over simpler and more common reasons ( humans do make mistakes).