It's Kishi's excuse to give Sasuke Hiraishin. But here's something to consider when people want to call themselves one of the following: Sage of Six Paths, Hagoromo, Indra, Ashura, Kaguya, inheritor of the chakras of the aforementioned, etc.
http://naruto.wikia.com/wiki/Chakra#Six_Paths_ChakraSix Paths Chakra (六道チャクラ, Rikudō Chakura) is the unique chakra of Hagoromo Ōtsutsuki, otherwise known as the Sage of the Six Paths. Hagoromo's chakra can be acquired by combining the chakra of both his sons, Indra and Asura, which can evolve a Sharingan into Hagoromo's own dōjutsu, the Rinnegan. This chakra can also be acquired from having the Rinnegan implanted. The Six Paths chakra, when combined with natural energy, brings forth the Six Paths Sage Chakra (六道の仙人チャクラ, Rikudō no Sennin Chakura), which is necessary for the usage and formation of the Truth-Seeking Ball. Becoming the Ten-Tails' jinchūriki or combining the Six Paths Sage Chakra with the chakra of the nine tailed beasts brings forth the Six Paths Sage Technique, which can allow the usage of multiple Truth-Seeking Balls. The chakra can also allow its wielder to float.
Hagoromo transferred his Six Paths chakra to Naruto Uzumaki and Sasuke Uchiha when they were near death, causing them to gain the Six Paths Sage Technique and Rinnegan, respectively.[10] This chakra allowed Naruto and Sasuke to directly harm Madara Uchiha when he was the Ten-Tails' jinchūriki, the latter of the two even bisecting him despite not having any senjutsu training.
Obito Uchiha stole the Six Paths Sage Chakra from Madara, to create his own Truth-Seeking Ball, despite no longer being the Ten-Tails' jinchūriki. From this, Obito was able to temporarily give the Six Paths Power (六道の力, Rikudō no Chikara) to Kakashi Hatake when he transferred his chakra to him as a spirit during the former's battle against Kaguya Ōtsutsuki. This power can amplify any technique and can also change its colour, as seen with Sasuke's Chidori and Kakashi's Lightning Cutter.
There are also Six Paths Yin and Yang powers, which can be transferred between individuals. Incredible feats can be achieved when the two powers are combined, such as unleashing a massive Chibaku Tensei capable of creating a moon and sealing a being as powerful as Kaguya Ōtsutsuki.
So according to this, in the Naruto-verse the Rinnegan can only be obtained by having the Six Paths Chakra, which is the chakra of Hagoromo. This was done in two ways: combining Indra and Ashura's chakras to evolve an Eternal Mangekyo Sharingan (Madara) or receiving it directly from him (Sasuke).
But here on the SL-verse, these special chakras that make Indra and Ashura so special happen to be within every Uchiha and Senju, respectively. Hence why every single Senju have the possibility to use Wood Release. And every Uchiha who has EMS can awaken the Rinnegan by attaining Senju cells. So technically, anybody who has properly awakened the Rinnegan, or currently have one inserted into themselves, already have Six Paths Chakra.
Now here's something fun to bring up: There's a fork in the road that can be chosen here. So you've got Six Paths Chakra, right? Well that would bring you to choose between two choices, either the Rinnegan or Six Paths Sage Chakra. The Rinnegan grants you what it usually does, but according to this, the Six Paths Sage Chakra grants you two things, Six Paths Flight and the Truth-Seeking Balls.
If I may bring my slightly-biased opinion here, with being a Uchiha/Senju hybrid with Sage Mode, I would like to introduce this whole Six Paths Chakra and Six Paths Sage Chakra thing into play. And before anybody jumps onto The Claimed, I would like to publicly announce my claim of use of the Six Paths Flight and Truth-Seeking Balls (not claiming it for only myself, but this is so nobody goes and gets the idea to keep these two things to themselves before we reach a possible verdict on this).
So yeah, Uchiha/Senju genetics win the genetic lottery.