It was a command because Zoro was demanding Luffy follow the course of action he wanted him to. It wasn't advice or a suggestion, Zoro told him outright to just do it.
I have already explained it. It can't be an order because he doesn't hold enough authority to order the Captain. Now it's your turn to explain how or/and why it was a command.
The fact that Zoro doesn't have the authority to boss around Luffy is exactly why his action of giving that command is disrespectful to Luffy's authority. You're dribbling on about how it was a request, it was not. The fact that Zoro outright yelled "OI LUFFY DROP IT!" while losing his temper all indicates it was a demand, not just a normal respectful request.
Giving Zoro the Vivre Card would have fulfilled Law's plan. Zoro wasn't part of Law's team. It was Law, Caesar, Usopp, and Robin/Nami, Sanji, Chopper, Momo, and Brook/Luffy, Franky, Kinemon, and Zoro. Law's plan was to get Caesar onto Green Bit, ditch Usopp and Robin, and for Luffy, Franky, Kinemon, and Zoro to destroy the factory as he distracted Doffy. Law would die, and the others would return to the ship. Law could have given Zoro the Vivre Card, which would have allowed it to still get back to the ship so they could go to Zou.Lmfao huge fail. Law had a plan setup, Zoro wasn't going to be on the Sunny team.