Vegeta knows that going Morikawa Saiyan will make him the most seme in all the universe. And given how the fate of the world seemed to be dictated by card games he decided to give Jounouchi's 'armor' a try to boost his stats given that Morikawa originally voiced Jounouchi and all. MAKES PERFECT SENSE.

I really should not be contemplating a folder of seiyuu known as "THE GINGER PERIOD"...