It makes sense considering that it's likely that Dededetour also took place after the main Story Mode - Queen Sectonia DX is the only form of her that you see in that mode, and Soul of Sectonia is the form beyond which only appears in The True Arena. Though by the time you get to that fight, she would have been defeated 5 separate times before, 4 of them by Kirby! No wonder she went insane…