Well I was implying that being able to draw in natural energy isn't all that is needed for sennin mode. The OP implies that it is something that someone can just awaken if they have the ability to gather natural energy.
I rooted that within the OP due to Sasuke's past use of Senjutsu. Back then it was force fed to him but he himself was duly suited to use it. Not only does he have Juugo's DNA within him that aided Kabuto in passively absorbing nature chakra, he has Hashirama's chakra, which might adhere to some use of Senjutsu, as the technique Hashirama gave him is supposed to respond to Senjutsu (scan is in the OP).