Well, during his battle with Naruto, Bee and Itachi he absorbed chakra out of the Kyuubi and got his mobility and youth back. Why didnt he do that earlier, Earlier much before he died?
He actually absorbed it of Killer Bee. He couldn't walk so he wouldn't have had any direct confrontation with a jinchuuriki before.
Because nagato was nowhere near naruto it was the paths fighting him.
If the real nagato tried pulling that he would of broke his hip just walking up to him lol