He could have won and killed Hashirama and still carry out his plan. He feigned death because he knew Hashirama won't allow for such nonsense and he couldn't beat Hashirama at that pointThat's not how a story works. Are you suggesting that it would have been impossible for Madara to have used Izanagi to revive himself then and kill Hashirama? It was part of his plan to get off with the Rinnegan(Hashirama's DNA) while having everyone believe that he is dead, so that he could carry on without interruption.