This is the best bug I've heard about in the game yet so far-- Drysc has confirmed that there is a known bug in the Blade's Edge plateau area which will cause everyone, when someone starts up the Bombing Run quest, to stop eating and drinking and stand up. It's a respect thing, you know? Stand up for the cause!
No, it's just a really, really weird bug, and a fix is on the way in an upcoming patch (I'm a little surprised they don't aim to fix it earlier, but apparently all that will be lost is the food anyone sits down to eat at the wrong time in Blade's Edge). Once again, I am dumbfounded at trying to figure out just how Blizzard's code works-- seems like they have the absolute weirdest bugs happen to them sometimes.