A big part of keeping any weapon working in extreme cold is keeping the weapon
in the cold and
not bringing it inside a warm environment where condensation can build up then upon leaving to go out into the cold it freezes or fogs up ones optics, hunting camp growing up taught us this nugget. So having a mud room that is unconditioned would be preferable if in a prolonged scenario where the situation is of the type we are not allowed to talk about here. But even bringing a cold weapon inside if it's maintained right, with the right lubricants and the lubricants have been given time to be absorbed into the surfaces of the metals that are being reciprocated against one can get away with much of the concerns of condensation.
There are oils and lubricants that have been developed to handle extreme cold. It's name is 'Lubricant Arctic Weapon' or 'LAW', this is to be used in place of CLP.
https://www.sportsmansguide.com/product/index/us-military-surplus-law-gun-oil-1-quart-new?a=2183264
Slip 2000 EWL is also rated down to -59* as stated on their website.
https://slip2000.com/pages/about-ewl-extreme-weapons-lubricant
I think the problem is there is a lack of people doing their due diligence in how to operate, maintain and use a life-preserving device to it's fullest. There are a lot of people who think just owning an AR15 is enough and fail to understand how to best put into service in different conditions the weapon. We Americans are an entitled, lazy bunch these days, we have forgot how to learn and process information, instead we want quick gratification rather than putting in the effort to fully understand things.
Our soldiers regularly train with Norway in arctic conditions, its a lubricant/software issue to remedy not a hardware issue. There have been countless videos, tests done on this subject, it is not a concern for AR15 usage in my opinion when one understands how to correctly maintain one's rifle in the situation one is found in.