My guess is no, as in no violation. As a ski pilot it's never come up with me, yet. I have wanted to get up to West Yellowstone, where the airport is "closed" during the winter, as in not maintained or staffed, my take is if I don't need fueling services, to use the bathroom, and don't need a plowed runway, I'm good to go. I sure as hell would not call anyone and ask first, but that's just me. No doubt they'd said NO just because.

While I'm up there I also plan to land at the old airport site right outside town, old as in not being there for maybe 30 years or more, but the open space is the same so no big deal. I've landed there a few times over the last 30 years but never on skis. I have a retired air force pilot friend who lives in a nearby condo, and he really enjoys my intermittent visits.