To each his own!
I would not put badges (in fact I have considered debadging my E420 entirely: I'm not sure it is anyone's business what the size of my engine is), but I don't understand what is so mythical about AMG. I have seen cars with some Brabus parts (but probably not engine conversion) put a Brabus emblem - thought it was ok.
I suppose the only difference is that Mercedes now acquired AMG. WOuld it have been as frowned upon to put on an AMG badge 10 years ago?