OK, let me tell you why the first Facebook post situation was NOT dumb.

If you're on a cell phone with a very low signal - 1 bar - that means your phone can get a control channel, but it might not be able to make a voice call. But if it can get a control channel, it can send a text message.
If it can send a text message, you can't reach 9-1-1 via text.
So, using logic, you would send a text message to the largest possible audience - in the case of many people, that's their Facebook "Friends".

So, given that we don't know if they could make a call - and I'm guessing they could not connect via voice call, they did the correct thing and used the communications tools they had, in a manner that - I might note- SUCCESSFULLY solved their problem.