Hey, don't be. It is not that he is inflexible. In fact, it is quite the other way around, usually. These players specifically sought him up because of his reputation for being a nice fellow. These would have been his third group and he did not have the time or the will to build up a full world for them. He accepted to try them up to see what kind of players they were and how HE COULD ADJUST TO THEM! But they were blunt, impolite and frankly, he should have asked me about them. They had approached me first but with two groups of 6 people with my Friday Night D&D once or twice a month, my work and my family, I simply do not have the time for an additional group.
On that one, I must disagree. Sharing the expanse is as close to what I would accept. The campaign world is my creation, my adaptation, my vision. As players, people are invited to build on that, but with certain parameters that I control for the sake of continuity. I don't mind a few campaigns in outlandish settings created from scratch once in a while. But if players are invited to play with me (or seek me out), then they agree to abide by certain rules, guidelines and expectations. If it is not to their taste, I would simply do as my friend did.
The only thing going for a DM's fun is exactly what players forget. The fun in being the DM is to build a world and to share it with your players. It is not to see players destroy it or its basis for the fun of their own agencies. If as a player, someone does not agree with my style, I do not mind at all. But if that person seeks me out, and want me to change everything to suit him and ignore the other players and groups playing in my world, it is a sure way to see me offer that player a one way trip exlclusion from my games.
A player's agency should be within the parameters of the campaign world. The player has to adapt to world, not the other way around.