You do need to keep in mind the state laws for North Carolina. You also need to consider Section 125 and COBRA. Your plan might not be under COBRA, but the umbrella is still there.
to mention is the idea of separation. You and your partner might be separated physically, but the state might not recognize that unless you have paperwork saying otherwise. North Carolina can be very picky about that sort of thing. North Carolina( I believe) is one state where they only recognize whether you are married or divorced. They do not recognize legal separation.
You asked about whether or not your partner(separated, but still married) can still receive the benefits under your work health plan. The short answer is yes. He can still receive the benefits. The only reason that they would not is if you had paperwork saying otherwise.
The paperwork has to argue "legally" that your partner is not eligible to get the benefits. You are still married in the eyes of the law so that probably will not affect you. What happens though if you do decide to get divorced at some point?
You will need to know that information if that occurs.
You also need to consider your options if North Carolina does recognize that you two are legally separated. Once that happens the Section 125 article kicks in. That means he will be kicked off the plan regardless of what happens. Right now the legal system is protecting your partner's portion of the benefits.
I suggest speaking with a representative from your health plan. Ask them what they suggest you do. They might say the same thing I have. It is better to get the official word from someone who knows the details better.