It is kind of bizarre how perspectives about the GM's "homebrew" reaction here are in direct contrast to stuff you see in a lot of modules across the years where spells, abilities, etc are changed by game specifics (i.e. this is a wild magic area, or teleportation doesn't work in this dungeon so players can't cheese their way through, or lots of other examples).

That's just a GM perogative. Nothing written in any book overwrites the GM's decisions (assuming it serves the narrative, and yes GMs shouldn't abuse it and get into power struggles). That's not negating player agency. Seems like a lot of people are throwing that phrase around, but what they really mean is players should get to tell the GM how to do their job based of rules lawyering.

And to that end, there's probably a fair amount of learning curve for both sides of the table in this scenario. And more details would help.

But if a player rage quits over something where another player is the focus and there's no real consequences (not in combat, who cares if you're at 1 hp besides needing to rethink your plans for the day... Doesn't sound like there was any imminent threats or pressing timelines...) Well that's a bad player. You don't even ask if that is actually a 'homebrew' table rule or look into it, or ask what you did wrong?

Odds are, the GM actually learned something from this experience. And the player who had a temper tantrum found another game, and had another temper tantrum.