Much as I dislike it when folks choose to hang on their props on the runway instead of off to the opposite side in the central pattern area while others are in the air I'd say the guy flying AGAINST the agreed upon landing approach was at fault. Especially if the other pilot had announced his intentions to land.

It's always a good idea to confirm the pattern before you take off with the pilots already at the line and call your intentions to use the runway to take off or land (or, even better, have your spotter announce it for you, to the other pilots).