I'd agree. The whole premise of fantasy games is just that...they're FANTASY games. This whole situation stinks of fantasy and reality becoming too much the same thing. You can't discuss morality seriously in a fantasy game. It's just not condusive to fun gameplay. You play your alignment and let the other characters play theirs. We have a hard a fast rule at our table: good and neutral alignments only. I can't see how an adventuring party can work through 20 levels of play without trying to kill each other if there's good and evil alignments present.
Problem is, his character is Neutral(or maybe even good, I can't remember) and mine is good. He was angry at me because he felt that the author of the adventure was an idiot because he set up a scenario that NO one would agree with. Who would agree with depose the rightful ruler of a country? Especially if you were good. That causes WAY more problems than it solves.
I tried to explain that the current High Blade is NOT the rightful ruler of the country. She backstabbed the rightful ruler and imprisoned him. Then she took over. The old High Blade even wanted to take over the city "legally". The laws let you challenge the current High Blade to honorable combat to replace them. He wanted to fight honorably and regain his throne. He just needed our help to get him to the fight without assassins killing him off.
So, pretty much any lawful person would want to see him restored. Pretty much any good person would want to see the city under the influence of a much less evil ruler. The leader of the Wizard's Guild offered to pay us all to see the deed done so most greedy characters had a reason to help.
Unfortunately, he was playing a "Neutral" noble of the city who had sworn allegiance to the current High Blade. He was perfectly happy with the current situation in the city(the peasants hopelessly oppressed in order to make the nobles rich and fat...which seems pretty evil to me, but...whatever). He said he felt railroaded by the adventure to go on a mission that was stupid. The adventure does tell the DM what to do if the PCs decide to betray the old High Blade and turn him in instead of helping him. He didn't actually try to stop the rest of his group. He just complained that he was OBVIOUSLY being railroaded but since he had no choice at all, he might as well do what the adventure expected of him.
But he's been complaining all season for the last D&D Expeditions season. It takes place in Mulmaster and the city is pretty evil. He feels that every time we saved someone's life it was pointless because they were likely evil anyways. Each time someone sends us on a mission to help someone he complains that helping one person will accomplish nothing for the city, it'll still be horribly evil and corrupt.
But as I mentioned way earlier in this thread, he complains about almost EVERYTHING: Monsters are too hard, rules are stupid, adventure writers are idiots who don't know how to write or edit, the DM doesn't let his plans succeed when they are outside the box, and so on.
This, IMHO, is my take on the demise of your party and play. Were you aligned similarly (not necessarily equally) you might not have even had to deal with this conversation.
Unfortunately, we are playing Adventure's League games. So, we have to follow the character creation rules created by WOTC. Those rules allow all alignments other than NE and CE. So LE is allowed. I can't change that. Though, as I say above, his character wasn't officially Evil. He just was profiteering on the suffering of others and felt that since he wasn't doing it himself, it wasn't evil at all.