I had a DM who would forbid actions because it wasn't within your alignment, when I ran, I decided to make a point. If he thought that DMs could make such rulings, then the same would apply to me. He played a NG, here are some snippets.
>"It's within your alignment to give the bartender a generous tip, you give him one gold."
>"It's within your alignment to volunteer, you spend the entire day working on an orphanage."
>"It's within your alignment to be selfless, you turn down the 500 gold reward."
>"It's within your alignment to protect people, you attack the muggers despite being outnumbered."
>"It's within your alignment to maintain the town's peacefulness. You retire and become the newly-elected mayor, roll up a new character."
He makes a TN
>"It's within your alignment to not care about others, you shove the beggar away when he asks for alms, and tell him to go work in the mines."
>"It's within your alignment to not choose sides, you desert the party. Roll up a new character."
Then he makes an evil one, he is fuming
>"It's within your alignment to kill people, you do so at the age of 12 and are hanged for it. Roll up a new character."
>"It's within your alignment as a chaotic evil to have sex with demons and succumb to temptation, you do this at level 1 and die. Roll up a new character."
The other players were perfectly in on it, but he didn't take the hint. He doesn't play in my game anymore, so at least I got rid of him and the other guys were killing themselves laughing after the session.