Not relevant unless you claim it can cover his whole skin. The shape of the scythe can go inbetween the bones and gain blood from his skin.Kimi's bones protrude from multiple locations on his body, coupled with the bone sword he wields in his hand. The scythe never makes contact.
No reason? Have you seen his fight with Naruto? Have you seen his fight with Lee? Base on manga, Kimmi has good reasons to not jump to conclusion, without understanding his opponent.Even without knowledge, there is no reason for Kimi to stand idly while his opponent catches distance and begins doing something. Kimi is a CQC fighter... there won't be a moment when he isn't on Hidan's ass. Even if unintentionally, Kimi never lets him make it.