Side-B needs both Icies off stage and synced together in order to work, which rarely ever happens and almost always requires Popo to use his double jump. They can't rise if they hit the opponent with it, and hitting them out of it 100% guarantees at least one Icie dying because they'll be forced into helpless.
Grabbing the ledge against Up-B forces them to use regular Belay, which is super easy to punish.
Distance-wise, Icies have amazing recovery. In terms of safety and reliability, it's one of the lesser ones in the game and one of the easiest to deal with.