Forgetting the politics of the situation, is ARC a registered legal entity? I see from the whois that the owner of the domain name at least is ARC:
https://who.is/whois/atlantareefclub.org
Based on what you said though, the hosting is in Jin's name?
If the hosting is in his name, you may be out of luck, but given that you have records of reimbursing him for it, there's probably legal standing to claim ownership.
Thoughts on talking to a lawyer and threatening legal action? Often times, a certified letter from a lawyer is enough to resolve an issue like this...