After Orochimaru reincarnated the Nidaime, wasn't he afraid that the Nidaime would be reincarnated in the dirt?

This is indeed the case, but there are several prerequisites that Orochimaru does not know, so he dares to reincarnate the second generation Hokage Jutu with confidence.

As the strongest ninjutsu inventor in the entire ninja world, the second generation Hokage Senju Tobirama invented countless ninjutsu and forbidden jutsu, including the BUG-level ninjutsu that can resurrect the dead? Reincarnation?. The conditions for activating the technique of Reincarnation in the Dirty Land are harsh, and the conditions for releasing it are also very harsh. It would be even more difficult if the person being casted wanted to release the control after being resurrected. When you use Soil Reincarnation, first of all, the soul of the person you resurrect cannot be sealed, just like when Yakushi Kabuto used Soil Reincarnation for the second time, Senju Hashirama, Senju Tobirama, Sarutobi Hiruzen and Namikaze Minato were all Naruto's soul was sealed away by the sealing technique of the ghoul, so even if he had the bodies of these people, he couldn't resurrect them.

Later Orochimaru released the souls of these people, so that they could be reincarnated in the dirty earth. Secondly, the reincarnation of the filthy earth requires the sacrifice of human beings as the soul container of the resurrected person. Finally, a certain amount of DNA from the deceased is required, which is the condition required for reincarnation in the dirty soil.

So, how can a resurrected person release the control of the caster? Either someone at the Six Paths level will contact you and directly help you unlock the control, or you yourself know the seal of the reincarnation of the dirty land and can unlock it. When Orochimaru summoned the first generation and the second generation for the first time, did he consider that the second generation would actually be reincarnated in the dirty earth and be able to cancel the rebellion on the spot?

There are only the following possibilities: 1. This is a plot BUG. At that time, Kishimoto had just started drawing Naruto, and he did not consider that the setting would become like this after the reincarnation of Kuzu. When reincarnation was added, the previous plot naturally became something incomprehensible; secondly, Orochimaru did not know at the time that the second generation could unlock the seal of reincarnation, so he used it boldly, but he could not Explain why the second generation didn't release his control until Sarutobi died. Did he have a premonition that someone would use the Earth Reincarnation to do bigger things in the future, so he held back? ; Third, the release of the Seal of Reincarnation from the Dirty Land and the casting of the Seal from the Reincarnation from the Dirty Land are two different things, just like your door key and your computer power-on password are two different things.