Without Kurama, Hashirama inherited more of Ashura's Chakra than Naruto. Just because he was older and had closer genetics to the original than Naruto did. With Kurama, Hashirama's reserves are only comparable to the Chakra shared to the Shinobi Alliance, which are portions of 50% Kurama. The thread is referring to Naruto after the war, which presumingly now has Full Kurama as Hagoromo told Yang Kurama to get back with Naruto. And if you refer to Rikudou Naruto, the answer is obvious. Naruto was given Ashura's original Chakra, and Hashirama is only centuries reincarnation.