There in an open field in a cheap cardboard box. Even if they were to flip it over, they would be in contact with the wet ground as well as having a wet box on there heads.
The ground right below the box would be dry, or at least semi-dry, as the rain just started. The box has a medium chance of preventing 'their' deaths that way. Cardboard isn't as flimsy as most people think.
A chance is better than sitting there and whining about it.