AJ, who said anything about sitting him down like a child? Do you ever (literally, has it ever happened? Yes, this question is rhetorical, I've seen it happen at least on these boards...) disagree with ANYONE? As an adult, which is what you claim you are, and we can only assume other gamers are as well, you should have no problem having a civil discussion with someone about something that bothers you. I know when I have friends over and they start goofing around and doing shit in my house that I don't want, I never say "knock that off or get the fuck out." I talk to them. You know, like an ADULT. That's an extreme example, but it serves its purpose.
As adults we are expected to be mature and address problems as they arise and not wait around for them to fume and build until we want to be childish enough to say "Do X or leave."
Here's my problem with your explanation. You state that you lay out the problem and give alternatives. That's a very dictatorship approach, and frankly counter to what you claim (fun for majority, group thing, DM as another player, etc). It doesn't fly. I like to give people the benefit of the doubt that they're mature and can handle problems. If they want advice, even better. That means they know their skills could use some work. Telling them to lay out alternatives does not help in any way, shape, or form.
So if we can agree that the first attempt should be discussion, good. That's all we need to agree on. Next we move on to these boards and their purpose. These boards are to offer advice for how/when/why to deal with said discussion. Sound good? Awesome.
Now that we know what these boards are here for, we can all agree that saying "kick him out" or any derivative of that does not deal with said discussion, right? That means it has no place on these boards. Open and shut case.