I can't remember where it's said, either DBs or in the manga but Kakuzu's ability to move is limited in full Domu.
Besides, KCM Naruto is powerless once Kisame fuses with Samehada.
He didn’t have Samehada at that point and still managed to slither away from KCM Naruto, but yeah even with Samehada no way he beats that version of Naruto I would say.
It also reminds me that Kishimoto admitted that he had planned for Hidan's scythe to have a number of special tricks, but "didn't have time to show them all".

You haven’t seen through one of the goats yet?
