I understand deadfall and that you could possibly stick a board but IMO there are a lot more dangerous situations you can encounter at a crowded resort. If you know what you're doing I would argue it's impossible to stick a board under a log. When we were "caught" we were literally 3' the other side of the rope.
Now my question is as I understand it most of the summit county (all?) resorts are US fores service land. If you skinned up the mountain, would the same rules apply to you? What if you accessed roped off backcountry terrain from the top of the mountain but didn't use a lift to get there?
"I would argue that is impossible"....um, no it isn't. No matter how good of a rider one is in the trees. While I would agree that it is less likely for a snowboarder. To ignore the danger of snapping of your leg is not being very aware of inherent risks of riding in the trees. It is like saying that a slope won't slide after digging a snow pit and coming to the conclusion that just because your pack test didn't fail that the slope won't fracture when you are riding on it. This type of rationalization is very dangerous.
As far as roped of terrain I think that even if you skin up and access backcountry through resort boundaries the patrol can take action to stop you. I believe they can do this just like when there is a wildfire and prevent entry due to safety concerns. Typically a resort won't tangle with a person unless the danger is very real. Resorts don't just make the call on roped of terrain for the fun of it. Yea patroller's can be uptight. But would you want to find someone dead or injured. Would you want to be the one to break the news to someone's family. If they were being real dicks they could have just taken your passes and 86'd you from the resort. Yea some of them get a little power mad. But they sure are nice to have there when you or someone you know needs them.
To find out for sure why not write and email or letter to your local Forest Service and BLM offices to find out for sure. You also should be able to find the lease agreements with resorts online I think.
Here is a link that might prove interesting. Pay attention to where it says forest closures.