he could but i don't see a point. He has done enough to earn his status. He trains the same and fights in the same weight class that gave him success. He either needs to find a way to win or hang it up.
He cant hang with the huge heavyweights anymore, keep in my his two losses in a row werent against the top hws either, he hasnt faces overeem or sergei or barnett or lesnar or cain or jds or mir or cormier, and im not sure how many of those he could beat either let alone bigfoot again