I'm sorry if this sounds ignorant but why did you think you could make a 100% peanut butter soap? Peanut oil maybe but peanut butter is made from the whole peanut not just the oil so how did you calc the lye? As far as I'm concerned there's more unsaponifiables in PB than there is oil?
Why not try it? The whole peanut will have oil present as well. Much like Beldi is made from olive oil and olive paste - there are unsaponifiables in the olive paste as well. Maybe that's the trick for pb soap - a certain amount of pb and peanut oil.