Whether the Preta path CAN absorb Senjutsu chakra was not the article in question, as Eric stated. The question was the amount of chakra needed to be absorbed to Frog, and eventually Stone a Preta path user. Naruto spammed his most chakra weighing techniques against pain, from multiple uses of rasengan, to probably his most expensive move, the Rasenshuriken. Now the full bodies worth of Senjutsu theory is garbagé (French Garbage; Really Bad stuff), if anyone watched the fight recently they'd know that for sure. Naruto stated himself that when the Preta path first absorbed a Rasenshuriken, it was simply a ninjutsu based one. Then, when he used a double rasengan, he stated specifically it was a sage version of the jutsu. (note I am watching as I am posting). Okay, I've watched the part in question, when the Preta path began absorbing chakra from naruto specifically. Naruto by that time had thrown a Rasenshuriken, and used a Double rasengan, so he had little more than 25% percent Sage chakra left, before the Preta path sucked him dry of the stuff. Then he gathered for no more than 10 seconds, if that, and the Preta path absorbed it. So he gathered basically nothing, maybe another ten percent. Maybe. So I'd say 35% would stone someone.