Continuity mistake: In the first shot it is seen, the fence of the power station that Doomsday is thrown at shows that gate part is slightly taller than the rest of the fence and has one sign on each door of the gate. But then moments later as Doomsday is plowing through the gate, it is now the same height as the rest of the fence, and only one sign is present, which becomes smaller and a darker color. Also two vehicles appear behind the fence that were previously not there. Also on the gate there is a sign on each side of it, but before it breaks there is a sign only on the right side. (00:22:30)
Answer: It was his way of coping with grief after Superman dies. Jimmy felt he needed to be in a new environment, away from painful memories. Similarly, Perry White turned to alcohol for solace, while Lois Lane sought out Clark's mother, Martha Kent for help.
raywest ★