With the understanding that Usopp mishandled how he went about defending the Merry, in spite of it being living nakama, and that the trust with each other’s lives is valuable for keeping crews together and such, I think that Zoro was a tad bit too assuming, even considering that Zoro tends to be a bit extreme in general, in regards to what kind of person he felt Usopp was turning into.
Zoro seemed to speak of Usopp as if he would be guaranteed to turn into someone who’d walk all over Luffy and treat his and the crew’s feelings as unimportant, as if Usopp would just leave and enter the crew whenever he wants regardless of how much that would massively affect the entire crew. I felt it would have made more sense if Zoro would have given his opinion just after Luffy’s fight with Usopp as opposed to after the Merry’s Viking funeral, because by the time of that funeral, I’m certain it was understood even by Usopp at that moment that that wasn’t abandoning nakama, something which he had previously assumed out of feeling useless and being insecure, but that it was instead letting the Merry go to Rest In Peace.
And I know Usopp was practicing making “returning to the crew” speeches when he returned to Water 7 as if the past doesn’t matter, when it does if it’s at least at the expense of the future, but somehow I think that he would have changed his mind on that as well regardless. In my opinion, I get the feeling that if Zoro wasn’t there, and Luffy had approached him instead, either Usopp would have changed his mind and would have been more apologetic after looking at Luffy right in the eyes, or would have realized at least by Thriller Bark that he can’t just screw around with peoples’ lives and that it’s not just his feelings and life that matters. I’m not painting Zoro as the bad guy here, or anyone as the bad guy for that matter, but me not simply wanting to boil it down to “Usopp says sorry, so everything is alright now.” which is how some people seem to simplify it, and considering how complicated I felt Usopp’s insecurities and feelings were in the first place. I suppose I personally would have at least been willing to see what Usopp would have ultimately ended up saying, had Luffy approached him first, after coming to terms with Merry’s death.