Jimbei joining to protect Luffy… Yeeeeeahhh no.
I dont like the basis for joining simply being for "protection" Every other member has joined because they honestly believe that following Luffy will allow them to accomplish their dream and goals and because of this they support Luffy in his own dreams and goals.
You are limiting the story too much, I think. I'm no writer, but given Jinbei's circumstance, even if he wanted to join the crew for one reason or another, Luffy still has to accept him, so I would think this is just one of the many building blocks Oda has and will establish prior to him actually joining the crew. We still have all of Fishman Island and in between for Jinbei's character to flesh out more. In that time, anything could happen. I mean, Jinbei joined the Pirates of the Sun even though he hated pirates, so he must have had motive. He disbanded the crew and joined the Warlords as well, and as we have seen almost all of the Warlords had hidden agendas or other motives behind that agreement, so it makes sense that Jinbei would as well. Plus, we know he loves peace and hates Blackbeard, which works as other motivation. Again, the real important thing to remember is that a lot can change in the course of an arc. We still know very little about him, but can expect to learn a lot more.
It's still a waiting game for Jinbei… You can't assume he joins when he isn't in such a position yet, we're still bound to be surprised by how Oda decides to have Luffy head to Rayleigh, if he does.
What does this even mean? Worst case scenario Jinbei could swim Luffy to Saboady Archipelago. lol.
And since he (Mister 3) doesn't threaten the monster trio he's a favorite to join right now.
Unfortunately personal preference holds no bearing on the actual story.
Why people want the likes of Jimbei to fight the Strawhats' battles for them is beyond me.
Again, preference has nothing to do with this. People need to stop ignoring actual arguments in favor of what they would like to happen. Also, since when as a new recruit "fought battles for the Strawhats"? Or are you saying they would fight alongside…? In which case, why does it matter who it is...? I don't understand your point at all.