It sucks, but it happens, and there's really nothing you can do.
When you get right down to it, most people that end up getting booted from a game are relatively long term friends that have recently gained issues making them disruptive to the game. If it's a new player, they don't get booted, they just never get invited back.
I had to boot a player just a couple weeks back that had gotten disruptive by griping about every choice other players made if it wasn't the action he suggested. Everything from planning and legwork to actual combat, gripe gripe gripe constantly to the point he wound up yelling at everyone at the end of the session and storming out of the house. We've been friends for a few years now, now we're not. His choice, not mine. It's a game. Get to serious about it, and things get unhealthy.
Sad thing about this one is that he had been warned repeatedly before, and had just been let back in the group (group vote) after being kicked for the same reason.