Those sellers may be business sellers, have permission to sell a certain type of knife on eBay. They may be an international seller where laws may be a little different.
Bottom line is with 7 billion plus listings on eBay at any one time, some that do break a selling regulation can slip the net, avoid being checked, and become listed. If they are spotted and reported like yours was, they too will be removed.
Your item has been spotted, it's under eBay's radar now so you cannot relist it for sale, as it would lead to serious selling restrictions.
@ardimart25