Just to make it clear from the outset, I don't have an opinion on the wearing of fur, in favour or against. I don't like animal cruelty of any kind (I'm a pet owner myself) but I also consider that the letter in question was ill-advised in terms of the likely response and totally irrelevant to the matter of the hobby. This post is written with that in mind and the intention of being humourous.
Adept: I understand you're here for an audience with the Emperor?
Petitioner: Yes, that's correct.
Adept: What is the nature of your request?
Petitioner: I'm here to discuss the matter of the wearing of fur amongst the Legiones Astartes. I'd like the Emperor to ban the practice, in the same way as the edict of Nikea banned the practicing of sorcery.
Adept: Erm, right. You do realise that the Emperor of Mankind is rather busy at the moment don't you?
Petitioner: You're trying to fob me off aren't you, stop me from raising this important matter with him!
Adept: No, no, not at all, I'm just pointing out that half of his armed forces have in fact rebelled against the Imperium, and have massacred many of the loyalist warriors of the Legiones Astartes on Isstvan 5.
Petitioner: Well I hope they haven't skinned those they killed to wear them as some kind of trophy!
Adept: Erm, you might want to take that up with Lord Curze...
Petitioner: No, stop trying to distract me. I'm here to talk about fur, not flayed human skin. Most widespread being the practice amongst the Space Wolves of skinning the wolves they find on their home planet and wearing the pelts. These are Legiones Astartes, they feel no fear, and they wear fully powered and environmentally sealed suits of armour, you can't pretend that they need the fur to keep warm!
Adept: I'm sorry milady, according to our records, there are no wolves on Fenris.
Adept: There are no...
Petitioner: I heard what you said, but I've seen these warriors, they wear wolf pelts across their armour!
Adept: I think you may be getting mistaken, I have most commonly seen such totems on warriors of the Sons of Horus, formerly known as the Luna Wolves.
Petitioner: Ah, I see, well, if the Emperor doesn't want to see me about this, perhaps I shall take it up directly with the Warmaster, can you tell me where I can find him?
Adept: Certainly ma'am, if you'll just see my colleague over at the departures desk he'll furnish you with a travel pass to the Isstvan system, from there you just need to follow the trail of dead bodies...