We are going round in circles a bit. On the one hand, asking somebody to leave a shul, however gently, is a very difficult thing to justify. But on the other hand, there does not appear to be any other solution to a difficult situation, as words do not appear to help.
What I am wondering is why he hasn’t listened to the gabbai. Either he doesn’t appreciate the problems he is causing, or he feels the complaint is unjustified, or he simply doesn’t mind causing a bother. As I asked earlier, is there any chance part of the problem might be some kind of personal issue, that he wouldn’t be inclined to respect the request because he doesn’t respect the requester? I’m sorry if this is unrelated, I just feel there seems to be more to this, for in most cases of a communal nature it would be natural to ask the Rav. So the fact that you didn’t appears to indicate, to my overly suspicious eyes, that it may not be a communal problem, rather a personal one. And this is purely conjecture, so I’m sorry if I offend.