Sasori Bio Question

[Sharingdork]

If Sasori himself (the puppet) is S-rank, why is it that you can make a Sasori bio at S-jonin, if you can only use S-rank at S-class ninja? Do you have to make the bio from before he was alive, and make it without Hiruko since S-jonin can only use up to B-rank jutsu? This makes it almost useless to have a Sasori at this point, as you can't use anything special to him; you technically can't even use HIM! I'm just confused by this, not only because of the fact that this bio is technically an S-rank puppet, but why would you make one at this rank, because there's almost nothing you can do with it. Are there any answers to this?