Interesting, I figured they would have tweeted first.
You say this as a joke, but you can twitter via SMS. In something like a drain where there is interference, it is quite possible for your phone to be able to send an SMS (which only requires a short, momentary connection) vs. calling for help (which requires a stable connection). Hell, you could even type in the text, hit send, and then throw your phone out of the drain so it has a better chance of sending (doesn't necessarily apply to this specific situation, but you get the idea)