Except what I was trying to say is that he didn't claim that right, and nobody granted him that right. If they had granted him the right to annex lands with a majority German population, then Danzig wouldn't have been the grenade pin of the world war.
The way it was framed was not that Hitler has a right to annex anything, but whether the Sudeten Germans have a right to secede from Czechoslovakia and join Germany, if that's what they want, and they're a majority in those lands.
ETA: What I'm trying to say is that people focus on ideas taken out of context like "appeasing Hitler" or "letting Germany annex some area", and lose sight of the context that the UK actually thought that the Sudeten Germans actually have a point. Or that the very reason why it looked like it's even possible to appease Hitler was because it looks like he's only demanding that a legitimate grievance be addressed, and the UK and France thought he'd only stick to such legitimate grievances. If anyone thought he's just demanding yet another random region, for no other reason than wanting to annex something, nobody would have assumed there's a limit to that.