I'm going to give you my advice based on my own experiences: drop him. I know it's harsh and I don't usually push for this sort of thing (I prefer the approach of talking with somebody about the issues), but from what it sounds like he's somebody who you can't really talk to about this.

I ran a The One Ring campaign recently on Roll20, and while the campaign is now in-person (all of the people who lived far away stopped coming to the session), back when it was on Roll20 I had to deal with vetting people over skype before letting them in.

One of the people I vetted was probably the most demanding individual I had ever met, and we hadn't even played a session yet. Most of the vetting involved him demanding I make the game what he wanted. Normally I'd totally be fine with making a game relevant to the players' interests, but the guy totally ignored the main foci of The One Ring Role-playing Game. He wanted huge amounts of combat and unrestricted morality and I couldn't offer him this. The One Ring is not about either of these things. In fact, in some ways, it's about the exact opposite.

The big problems, though, were his tableside manners. He wanted to bring up religion and politics during the game (which are both not permissible topics when I'm game mastering). Additionally, when I mentioned that my sessions are a gender-neutral zone (meaning no unwanted attention given to the girls of the group, or vice-verse), he said I'd have to be lax on that since he might offhandedly flirt with them because, "He's a charmer."

I dropped him. I let him know straight-up that he is not the right fit for the group since it seems as though he's looking for something a little more "munchkin-y", and not as narrative as what me and all of the other players are looking for.

So, why am I telling you this? The point of the story is, If the guy is not being harmonious with the group, drop him. I could have kept my dude, but in the end it would cause problems if he keeps pushing upstream against the river current. Don't let your game go sour.

TL;DR:

You are not being unreasonable for following what the majority of what your players want and putting the kibosh on this character concept. The other guy is. Either he needs to respect the groups' wishes or he's not going to be right for the group.