Timeline of events from what I can tell.

Tornado watch issued.

First tornado warning. They took shelter as they are supposed to. Didn't get hit. Warning expired.

Workers now ask to leave and are threatened with being fired. They continue to work for a few hours.

A second tornado warning is issued. Sirens go off. Workers take shelter as they are supposed to. They get hit by a big tornado and workers die.

I'm just amazed at the responses I've seen on most of Reddit, because this is how it's always been at every place I've worked for the last 25 years. Even in call centers where we could and did work from home when there were things like snowstorms. It never even occurred to me people would expect differently and I've never seen coworkers expect such. You don't just get to stop work because there's an heightened threat of tornadoes. Getting hit by a tornado is just such an unlikely thing to happen even under a watch. Much less a monster one like this.