Thread:Omega64/@comment-4503935-20190703001710/@comment-10330822-20191117003839

Instinct. Jiraiya mentioned that Minato's instinct was very strong, and when he felt something was right, it usually was. Likewise, he wasn't the sort of person to do something without a reason, which is why Jiraiya was confident he put the Nine-Tails in Naruto so Naruto could learn to control it.

Logically, if Tobi could control the Nine-Tails, he could control other Tailed Beasts, he was shown to do. That probably would have been too much for Minato. However, if Naruto was made into a Jinchuriki, then the natural talent he inherited from him and the bloodline he inherited from Kushina would allow him to surpass Tobi's threat by becoming perfect Jinchuriki.

In short, it's like Minato forsaw the battle between Tobi and the Six Jinchuriki and Naruto. And he knew nothing short of a perfect Jinchruiki would get the job done.