The accident involving the Rouses had nothing to do with the fact they were diving air as bottom gas.
Shortly after entering the wreck Chris Jr. was trapped by falling debris; loosened silt reduced the visibility to nearly zero. Chris Sr. entered or was already just inside the wreck and began to dig out Chris Jr., further reducing the visibility. After Chris Jr. was freed, the two divers were unable to follow their line out; according to statements by Chris Jr., and examination of their equipment, they evidently began exploring with line for a new exit. During their exit, it appears Chris Jr. experienced some trouble with his primary regulator and switched to his secondary regulator, but it was taking in water. At this time Chris Sr. gave Chris Jr. his secondary regulator and they continued out of the wreck. After finding the exit, Chris Jr. noted it had taken 31 minutes for them to get out, 11 minutes longer then their planned bottom time. They were able to locate only one stage bottle (EAN60) and were so low on air with no more time at depth to search for the anchor line or the remaining bottles they left for the surface. They may have attempted some decompression in mid-water.