His plan is to steal the ten tails from Kara and give it to the leaf. He has to utterly destroy kara if he intends to survive. That means defeat Jigen and take the ten tails. He probably thinks that Boruto or Sarada (Naruto or Sasuke) could be it's vessel and use them to defeat Kara. At the same time make the village an ally with all the resources he needs to continue his work.