What you did there. I see it.
At first i thought it was Karin, but now i have no clue
Some anon called Jiraiya. I think he's right.
Itachi planted another Genjutsu inside of Izanami such that if Sasuke dies, Kabuto would be forced to revive him.
or maybe a simpler route.
The only way to wake up from Izanami was to learn the error of his ways, thus he came to help with his medical ninjutsu.