Literally who said Zoro wouldn't have the authority as Luffy if being captain?That's because being captain means you have that authority. Zoro, however, isn't the captain, so this is irrelevant.
Sanji didn't argue because he felt the same way from the beginning. I'm asking for a scenario where Sanji and Zoro expressed opposite views, and then Sanji changed his mind because of Zoro.
Zoro has absolutely zero ability to do any of those things. He can't decide who joins, who are their allies, what island they go to next, and who they wage war on. The difference between Zoro and Luffy is that if Zoro tried to do those things, the rest of the crew can say no.
No shit he can't do that since he's not a captain :|
Zoro could and I believe he is the first mate of SH's.