Don't quote me on this, but I believe there's some more nuance to the cellular band issue. What's restricted, AFAIK, isn't simply receiving traffic on those frequencies in and of itself, but:

1. Decrypting those communications if they are encrypted

and

2. Selling equipment designed to receive on those bands.

Of course there's not much purpose in sitting around listening to the digital chirping noises of encrypted traffic, but as I understand it, if that's your hobby, that part is actually legal.

(Also a licensed US ham, not not an expert in anything in particular and definitely not a lawyer)