Consider the following:
- The Toad Scroll was passed down to us by Jiraiya, who was genuinely fond of us and would have stacked the deck in our favour as much as possible. He probably left us some shinies with the Toads, such as... pre-arranged contracts with powerful summons.
- We can't say the same for the Snake Scroll; for all we know, we'll have to start from scratch.
- Powerful summons require a lot of chakra to summon.
- Noburi has five times Hazou's chakra.
If we give Noburi the Toad Scroll and Hazou the Snake Scroll, we'll be able to summon powerful Toads the moment Noburi picks up the Summoning stunt. If we do it the other way around, Noburi won't be able to summon powerful things because of lack of contracts and Hazou won't be able to summon powerful things because of lack of chakra.