Man buried for four hours in 4' deep mud: thixotropic, rheoplectic, or something else?

Man immersed in mud for four hours in Atlanta, Georgia

An amazing event and rescue in Atlanta, Georgia, was briefly on the CNN.com news this morning. It's not clear how the story was pieced together yet, and the rescuers have no idea of the identity of the man involved or how he came to be stuck in mud.  At a construction site, there was a pool of mud estimated to be four feet deep. It appears that the man did not fall from the site, because it would have been a 30' fall and, aside from his mud trauma, had no other injuries.  He apparently wandered into the mud, and struggled to get out of it for a few hours before succumbing to cold and exhaustion (it was 50 F) in Atlanta this morning. Rescuers could not reach him without danger of becoming trapped in the mud themselves. Eventually a female paramedic reached him and kept his airways open until rescuers, using boards from the nearby construction site to fashion a bridge out to him, were able to pull him out. The video above shows his rescue, and he is apparently doing fine in the hospital.

The video compared this situation to quicksand, but I'm not sure that the analogy is correct. Quicksand is an example of a "thixotropic" fluid, one that starts as a solid and becomes weaker when it is shaken, aggitated or stressed. If my interpretation of the video is correct, this mud became stronger as he struggled so it may be an example of a "rheopectic" material, one whose viscosity increases the longer it undergoes shearing. Such materials are fairly rare, but of increasing interest in military and sports applications where a major goal is to create materials that reduce the stress due to impact. For instance, a shoe that incorporates rheoplectic materials in its cushioning might help protect the feet of runners, jumpers, and hurdlers. Helmets and body armors with such materials would reduce body trauma from projectiles.

Or it may be some other wonderful wierd behavior! Readers comments welcome!