I’m not sure what you mean by “oda can’t count”. Are you referring to that scene when Luffy said he wanted at least 10 men?
Luffy not referring to himself was just an editor’s interpretation of that scene so I don’t put much weight into it. Plus Oda could have changed his mind if that was his original intent. It’s been 25 years after all and Luffy was vague by the total amount of crew members he wanted.
10 total crew mates is a nice round number so it makes sense to me. I just don’t think there’s enough time left in the story for a new crew mate without it seeming like as ass pull unless it’s somebody like Vivi.
My problem with her is tha she’s fodder tier and would be a liability for the SHs constantly needing to be protected. Could be wrong but that’s just how I currently feel about it.