So, as of 638 the Sage of Six Paths became even more badass than before. Why? Because we now know that when he created the moon, he was no longer a Jinchuuriki. When Obito sealed the Ten-Tails, he absorbed not only it's chakra, but even it's physical body. So for the Sage to entomb the Ten-Tail's husk within the moon, he had to have released it from the seal and forcibly separated it's chakra into the Tailed Beasts already.
So, even as a dying old man, he still had enough raw power to do something like that. That's a bit scary.
So, even as a dying old man, he still had enough raw power to do something like that. That's a bit scary.