Repeater owners can limit who uses their repeaters. They cannot dictate who uses frequencies. Nobody owns frequencies. A banned ham could still attempt to use the repeaters (by using the input frequency) or causing trouble by transmitting on the output frequency, but historically the FCC considers this against good amateur practice, and worse, they consider it to be willful interference.
Doubtful. The state civil court has no jurisdiction in the matter.
There are two issues in play here, A) limiting the use of a repeater, and B) access to the C-Bridge which links a bunch of repeaters together and bridges to the global DMR-MARC network.
The Plaintiff clearly has no grounds for issue A. This is solely under the jurisdiction of the FCC, and historically the FCC supports repeater operators limiting user access, no matter what the reason, full stop.
As for issue B, the Plaintif contends that he "joined" a "club" and thereby is a "member" with right to "due process" regarding access to the repeater system, according to North Carolina statutes that governs clubs and associations. NC-PRN clearly states on the their website that that they are not a "club", they have no "members", no dues were paid, etc. So the North Carolina statute governing Plaintiffs assertion does not govern.
Details were not given in the Plaintiff's Complaint that grounds his assertion that he "joined" a club. Was it simply a matter of getting a DMR-MARC ID and then programming his ID and the local NC-PRN repeaters access info into his radio (Frequency, slot, color code, talkgroups, etc)? If it was nothing more than that, NC-PRN is clearly in the right. Thousands of hams have done the same thing, including myself, with my local DMR repeaters, and the Hoosier DMR network, and I in no way believe that I ever "joined a club" just because I gained access to the DMR system, nor do I have any other grounds to think so, and I'm sure many people would be willing to testify to that in court.
(This post is my opinion only and does not constituent legal advice)