When we finally get to meet the burned man it turns out that yes he was burned and thrown into the grand canyon, however he landed in a river which was irradiated and brought back to good health by ghouls living in peace and solitude. The ghouls alone weren't his saving grace; he himself was turned into a ghoul and the irradiated gulch of the Grand Canyon revitalized him. When the leaders of the Ghoul settlements of the canyon got together to decide what to do with a former Legionaire Joshua had an idea, he would train them to fight. He utilized the hundreds of feral ghouls at the farthest, and deepest, end of the Canyon. By Leashing them to plows, training them to protect live stock and fitting them with armor which was tested to withstand the the blade of the Legions O so coveted Machete he begins to plan his assault using the Colorado as his guide.