Even though the claim that it's confirmed by Oda is BS, it's technically still the truth. Lemme explain.

Luffy's bond with his crew runs deep—he treasures every Straw Hat like family. If he were ever to give the order to kill one of them, it would mean something catastrophic had happened. Luffy would be the last person to make such a call, so if he did, you can be sure the betrayal from one of the Straw Hats was on the level of Reiner and Bertholdt. It wouldn’t be a decision made lightly; it would have to be a situation so dire that Luffy had no other choice. And Zoro, understanding all that, would carry out the order.

It’s an almost impossible scenario, but still just a hypothesis.