For Jiraiya, rather than spending vast amounts of the village's manpower and resources to protect Naruto, it would be better to train Naruto into a Perfect Jinchuriki like Killer B of Kumogakure.
That would not only save the manpower needed to protect Naruto, but also turn Naruto himself into an important combat asset for the village.
It was just that, compared with the other Tailed Beasts, the Nine-Tails was far too special.
Even the powerful Jinchuriki of the Uzumaki Clan in the past had only been able to suppress the Nine-Tails. None of them had managed to reconcile with it and become a Perfect Jinchuriki capable of maintaining their own will.
The later 'Nine-Tails Attack' had caused the higher-ups, and even the entire village, to develop a deep fear of the Nine-Tails.
That was also why the village higher-ups were relatively tolerant of Sasuke.
Even if there were still doubts about his having controlled Naruto when he went berserk, and even if he was an Uchiha hated and feared by the higher-ups, as long as he possessed the potential to suppress the Nine-Tails, he was what the village needed.
And now, Yakumo had mastered 'Wood Release'!
As everyone knew, First had not only pacified the chaotic Warring States era, but had also traveled throughout the various nations, sealing away the Tailed Beasts scattered across the Shinobi World one by one.
There was no doubt about 'Wood Release's' ability to suppress Tailed Beasts!
Yakumo, who had mastered 'Wood Release', was equivalent to an insurance policy—a safeguard that could suppress a rampaging Naruto at any time and in any place.
And precisely because they now had such a safeguard, Jiraiya had come up with the idea of having Yakumo assist him in helping Naruto train to become a Perfect Jinchuriki.
Tsunade did