The snow-dependent activities are gated by the season, so timing decides availability. Camping and snowshoeing are at their best in November and early December when there's deep snow to camp on and walk over, and they get progressively harder as the season melts out. Kayaking runs across more of the season but is still subject to ice and wind on the day.
This catches people out. Someone books a late season trip specifically to camp, and by the time they arrive the sites that work for camping have lost their snow.
Two other things worth knowing. Activities are usually pre-booked and they do sell out, sometimes well before departure, so if one of them is the reason you're going then book it at the same time as the cabin. And some activities run during a landing slot rather than alongside it, so joining one can mean swapping a shore visit rather than adding to your day. Ask which it is on your specific ship.