When he had seen just how absurdly powerful Uchiha Yuzhen was in their previous fight...
He had also begun to think that Madara and Black Zetsu's plan to banish Uchiha Yuzhen to another time-space might actually work.
After all—
If that monster really remained in this world, then even with him joining the Akatsuki, whether they could successfully capture the Tailed Beasts would be a big question mark...
There was no helping it...
After witnessing how monstrous Uchiha Yuzhen was, even if he didn't think he would lose in his prime,
he couldn't deny that he was severely injured now.
Even after thousands of years of recovery, he could only manage the level of strength he'd shown when fighting Uchiha Yuzhen before.
If he unleashed any more of his power...
he would have to sacrifice his lifespan, and that was something he absolutely couldn't accept.
As long as he didn't unleash his power, Uchiha Yuzhen was invincible on this planet among the shinobi still alive in the Ninja World.
In that case...
If the plan to capture the Tailed Beasts didn't go smoothly, Kaguya couldn't be unsealed, and he couldn't achieve his goal.
Wouldn't taking the risk of stepping into the open and joining the Akatsuki have been pointless?!
Besides,
he had a fallback plan.
If he remembered correctly, when he and Kaguya had come from their homeworld to carry out the harvest,
that wretched woman had brought Li, the Noble Phantasm capable of traveling through time and space, to the Ninja World as well.
His plan was...
after banishing that monster, Uchiha Yuzhen, he would take some time to find that Noble Phantasm.
Once he had gathered everything needed to unseal Kaguya...
he would use that Noble Phantasm to travel through time and space and bring back the banished