The devotion to your cult is impressive. First of all, I looked into it. The Japanese fleet didn't maintain radio silence. Here is what one intercepted radio message said. Sent by admiral Yamomato from his flagship of the Japanese fleet to Japan. "The task force, keeping its movements strictly secret and maintaining close guard against submarines and aircraft, shall advance into Hawaiian waters, and upon the very opening of hostilities shall attack the main force of the Unites States fleet in Hawaii and deal it a mortal blow."
Why was this and other messages sent? Because admiral Yamamoto himself didn't want to pull off a surprise attack. The Japanese knew very well that the American public was against getting involved in another war. Which they were. Especially in Europe. The Japanese weren't that stupid. They knew full well that an actual surprise attack would inflame the American public. Which it did. Also, the Japanese fleet had our fleet seriously outnumbered. If our two fleets had met in open battle, the Japanese most likely would have won. FDR wanted a surprise attack. The Japanese basically had no worries.
Next, what commander Nagumo wouldn't or wouldn't have done didn't matter in the slightest. They could even have actually invaded Hawaii. It wouldn't have mattered. We eventually would just have taken it back. And in so doing, weaken the Japanese forces even more. We wouldn't have had to chase them around the western and southern Pacific. We could have finished most of them off there. And your thinking that the U.S. would have caved in to Japan is just wishful thinking. The Japanese could never defeat the U.S. And they knew it.