What makes you think they haven't been left speechless. Only thing they say is, its tradition. Also, you have provided nothing of value to this discussion. None of your antics worked so your last resort is to try intimidation. This wont work either. You are a coward. Let me rephrase it, you are a white privileged coward. No nihang, no hazuri can harm any Gursikh. Their leader Santa sinh died in pain for his evil act. Here is a history lesson. Bhagat prahlad ji was up against a tryannt like the nihang Singhs and Hazuri Singhs have become today. Vaheguru himself came to destroy the tryannt that wanted to hurt his bhagat. Killing innocent goats for blood is an evil act. Bhagat kabir ji says, who will cut a throat to have meat with their bread/roti. Meaning who would hurt another in the process of obtaining a meal. The nihangs kill the innocent goat to obtain its blood primarily. It's done because its a customary ritual, a dishonest ritual. They physically cut the throat of an innocent animal. For such a crime there is great punishment.
Do you have any Gurbani to support your thought process? If not, then you are using your manmat to think for what the Guru would say. When a Sikh gives his head. That means leaving personal feelings, opinions and views behind.