Given Hyuga Kagami's current situation, the safest approach was naturally to set a trap, lure Otsutsuki Toneri down from the moon ahead of time, defeat him in battle, and eliminate this hidden danger.
But he had already used this tactic several times before.
Especially during Akatsuki's last attack on Konoha, when he had used the resonance between Tenseigan to draw out Otsutsuki Toneri, nearly getting Otsutsuki Toneri sealed by Nagato's Planetary Devastation and causing him to suffer a devastating loss!
Having learned such a painful lesson, no matter how inexperienced Otsutsuki Toneri was, he would not fall for the same trick so easily again.
And the situation in the Ninja World had already reached its most critical point.
Not only had Obito become the Ten-Tails' Jinchuriki and gained true "Six Paths-level" strength, but he had also used his absurdly overpowered space-time ocular technique, Kamui, to take advantage of the chaos of the Fourth Shinobi World War and seize the Three-Tails and Seven-Tails, the two fish that had slipped through the net. This had allowed the Ten-Tails within him to revive even further.
Under these circumstances, Hyuga Kagami no longer had the time to slowly plot against Otsutsuki Toneri.
Perhaps before he could even get to Otsutsuki Toneri, Obito would have already completely swept through the Ninja World and followed the clues to the Rainbow Ice Wall.
Or perhaps Obito would directly launch the Eye of the Moon Plan, allowing the light of the Infinite Tsukuyomi to shine upon every inch of the Ninja World!
When that happened, Hyuga Kagami's ritual would inevitably be exposed, because the Eye of the Moon Plan involved projecting the Infinite Tsukuyomi onto the moon and using the moon to reflect the ocular technique across the entire Ninja World.
So once Obito launched the Infinite Tsukuyomi,