I think you'll find that almost all recipes for cooking pork or beef under a crust (usually under salt or salt dough) call for a tender cut such as the loin or tenderloin, not a tough cut like the leg or shank. I'm pretty sure that Gideon's leg would have turned out overcooked, gray, and tough from baking in clay.

If you're going to cook a human leg, why would you cook it wrong?

Celebrity chef Jose Andres is supposedly the show's culinary adviser. So how did they manage to screw up the cuisine on this episode so badly?

Terrible cooking in this episode. Why would you ever cook red meat in clay? You cook fish in clay, or maybe chicken, since it's basically steaming, but certainly not red meat. And the meat looked like skirt steak to me, not a leg. Not to mention that I think I saw Hannibal holding a knife with his index finger…