If it's not in the league bylaws, i don't believe he has a leg to stand on. It's an ethics situation, but i can understand how he feels. I too, like and give 2 lane courtesy, unless directed specifically not to, as in some tournaments. The only thing i can suggest is 1) when you see him up, take the extra second and wait 2) he should realize that you aren't giving 2 lane and take the extra second to let you go first. One question i have is how long does he take in his pre-shot routine? Is he a human rain delay? That could also influence my answer. If he's up on the approach, set, and you walk up, then i see his point. I know in my leagues, there are certain people that will walk up on you no matter what, so i know those people and take my time and let them go first. It also matters what the game is like. Does he have the front 7,8,9??? There are many different factors that come into play. I know you will see responses about "If you are focused it doesn't matter." but it does when all of a sudden the guy slaps one out or stomps because he left a 10. Just my thoughts. Good luck with the meeting, but if it isn't in the bylaws, you have nothing to worry about.
