DL is the only SkyTeam member that flies from the US mainland to HNL. However, you can use AS from the mainland to Hawaii, as they're a DL partner but not a SkyTeam member. For some reason, there are extra restrictions on what HA flights can be booked. Since the JFK-HNL flight is new, DL's IT might not have yet figured out how to prevent you from booking it, so you might try to get a seat on it.