But, it was probably obvious that something happened to Isobu's Jinchuuriki if hia chakra completely disappeared without a Jinchuuriki and then Kiri would be in uproar and that would cause problems. Obito didn't know Rin was a Jinchuuriki. Zetsu also probably wouldn't let Obito bring Rin with him because she might tell him what really happened if she was resurrected and that would ruin their plans. Also, it's highly unlikely Obito knew about Edo Tensei or what the Rinnegan is capable of at the time to consider that Rin could be brought back.