Great question, @Cowboyjr1982! Items over 20 lbs aren't eligible for shipping. I'd recommend reporting the other item so that our team can investigate and remove!
Items are only marked as shipping enabled by the seller. In this case, I'd assume the seller didn't mark the weight of the item properly which allowed the item to go through and be posted. Within the posting flow of listing an item as shippable, the seller must pre-select the weight limit. We don't go in and mark items as available via shipping. This is why reporting the item is the best route, or letting the seller know that their item doesn't qualify for shipping.