I don't agree. I think that a quite defined social structure is shown in character interactions, but the nose is not a metaphor. The disappearance, reappearance, and disguise of the nose are simply key events in a story reflecting a classist society. Kovalev repeatedly announces the important acquaintances he has in attempt to gain cooperation from those who cannot help him with his predicament. The fact that the nose is a state councillor is not a coincidence, however. Gogol uses this opertunity to demonstrate Kovalev's altered behavior when speaking to men in positions higher than himself.