Yeah I think it's a COVID thing. They told me I could walk over to the Mauna Kea beach but I wouldn't be allowed to sit in any chairs or use any towels. The front desk staff were uniformly unfriendly so it may just be a made up rule. When I drove over for dinner the gate guard just waved me through without bothering to check if I actually had a reservation. I doubt anyone at the MK would notice or care.