How are the Japanese going to threaten Hawaii directly?
As of June 1942, there were 2 combat divisions in the Hawaii Territory with a total of over 100,000 ground troops, the USAAF had over 15,000 men, 200+ fighters, and over 100+ heavy and medium bombers. That's not counting the USN and USMC aircraft stationed and in transit there. There were functioning radars around the islands. As Calbear stated above, the USN knew that the IJN had to be at their utmost logistical limit just getting to the islands, trying to stay any length of time is just not going to happen. What can they do? A couple of days worth of air attacks against prepared opponents.
With travel time back from Midway, refitting and rebuilding the lost aircrews, and travel time to the Hawaiian Island, the earliest the IJN can get there is mid-August, probably later. You don't think that the US would be loading up the islands with every available airplane to ensure its defense? As crazy as the Japanese are, even they realize that another go at Pearl Harbor is a bad idea.
I see the Japanese as having two viable alternatives in the above scenario. Either proceed with Operation FS which has a high probability of getting defeated or making another attempt at Port Moresby, that will be tough but it has a higher chance of succeeding than Operation FS. The Japanese may have not realized it but by June 1942 they have reached their culminating point. They cannot keep advancing with facing major defeats in whatever they attempt.