I don't see how this can be considered griefing, they are just playing the quest the way it's supposed to
btw, the ddoor thingie, it's kinda stupid to still be using it, the reason it was used in the past was because of a bug that if you recalled and left the group you could still get the completion, that bug doesn't exist anymore, but I guess some people has not enough intelligence to ask himself why something is done in a given way and try for a better one