I agree with everything you said. When one partner is unwilling to compromise about anything the issue cannot be resolved. Everything should be open to compromise and the word nonnegotiable should not be an option. The foundation of a marriage should be built on compromise. Your husband is being unreasonable. This seems to be a power struggle at this point that you are losing. He may feel that if he gives up some of his power then he loses the fight. When in fact if he compromises he makes the relationship stronger. You need to get him to understand that compromising is not losing. He can have some of his friendships within reason.
I would love to tell you what to say that changes his mind but that term means what it says. That he is not going to budge. I would urge you to check out my favorite resource on communication between couples - Mars and Venus Together Forever.