The BFG AT, particularly the new one, isn't a M&S tire except for labeling purposes, nor is it really a winter tire (I am running the new KO2 - great tire). That's a major problem with these ratings - they are based on standards that don't really reflect performance.
The reality is that the "in the ditch" tires are all highway tires. You can put an HT on any vehicle, and most OEM rubber is HT, and you have an in-the-ditch vehicle. After that, traction becomes about the interaction between vehicle and a tire designed for superior traction in certain conditions.
As an example, trucks - that is the solid axle kind designed with 4x4 in mind - put traction to the ground differently than cars. This is part of the reason a 4x4 on a good off-road tire will idle circles around 2WD with studded snow tires, and, amazingly, also corner and stop. How do you account for this in tire laws? It is only all about tires when you are talking HT tire standards.
I've been on Floyd Hill when it was so icy that everybody on the road was either stuck or trying to get to the frontage road where they where sliding around trying to park. AWD, SUV, everybody. I just drove around them all (I-70 was just about to close), took the frontage road, and used granny low gearing to descend. Never slipped a tire. Another 4x4 followed me. By labeling, both of us were only on M&S tires, and many M&S tires can hardly get out of wet grass. So that's a ridiculous standard.
I have another idea. They need to establish an I-70 Rescue certification, and once you have it, you can go around all road closures if feasible on the premise of being able to assist others .