Walking out of Burning man now makes sense for those physically able to do this and survive

 Why?

Because much more rain is expected which is just going to make conditions worse and worse. So, walking out to civilization makes complete sense for those capable (in all ways) of surviving this. But, likely some of the people walking out might not make it too. For example, if it takes more than one day to walk out and the maximum even under perfect  conditions a group could travel on foot is about 20 miles. I'm not sure of the topography exactly of Burning man but just the wet clay could be a problem. So, if you needed to walk more than 20 miles and then you had to set up a camp on the clay wet mud that would be a real mess too and then you would likely be carrying another 20 pound of mud because you wouldn't have enough water available probably to wash off your ground cloth that would be caked in clay mud. So, then you have your hands covered with this really sticky clay mud. So, some of the people might not make it with the extra weight of the clay mud caked on their boots and ground cloths etc. So, walking out of Burning man is an iffy proposition but I'm not sure it's a real choice because it's supposed to rain a lot more and get worse over time at the burning man location. And some people get high there on various drugs and that might cause their deaths in this kind of situation too. the Desert in these conditions is very very unforgiving short of a helicopter picking up people and taking them home to wherever they live or to an airport to fly home to wherever they live.