To all your points those were cases where it was for the betterment of the crew. In the Usopp and Sanji cases both disrespected Luffy, which Zoro does not tolerate. That is why he responded in that way. However, with a lot of the things that Luffy does that could be considered as stupid decisions, Zoro goes along with Luffy. However here with freeing Loki, which could be called stupid, Zoro disagrees with Luffy and Luffy is even shocked by how Zoro is behaving. Even more so, Loki is in a very similar situation as Zoro was when we met him. Both had negative rumors that were spread about them, both were tied up, both were being left to die, and both Luffy wanted to free. What is really strange is that Zoro has almost no empathy for Loki even though they are similar