Reminds me of both times when I upgraded to the latest Xbox 360, transferred everything across including my GamerTag and then had to create another one just to get past the initial menus, then sign in as normal with my exisiting GT.
I'm assuming it's like that, if so then I agree, it's completely silly... a 'temp' account isn't like setting up a full PSN account though is it? I hope not as I'm sure when I get my Vita I'll want to use my PSN ID with it asap so I can get on with downloading SSDD.