On the one hand, this seems like a long-overdue functionality. Being a Bostonian, the Boston Marathon bombing immediately comes to mind as cell service was clogged while people attempted to reach loved ones to try to confirm all was well. Ditto for the all-night car chase through Cambridge and Watertown a few days later and the following day when Watertown, Boston, and surrounding areas were almost completely shut down by police during the manhunt.
Ditto for other events that have happened throughout the country.
On the other hand, an "I'm okay" status update accomplishes the same thing.
When I checked Facebook today, I received a notification telling me that a friend of mine in Orlando was marked as safe. That's good. But this is now, what, a couple of days later? Not to mention the fact that this friend of mine is a married woman who works extremely long and late hours and whom I had no reason to believe would have been anywhere near the vicinity of the Orlando shooting. All this notification did was remind me to worry about other FB friends of mine in Orlando (needlessly, to be sure).
So it's kind of a blessing and a curse. Still, at least FB's innovating here.