The theory that Israel could make up for its massive numerical disadvantages with some better training, tactics and morale, with some caveats ("If this assumption should prove wrong, Israel might well be in trouble ..."), doesn't really match your claim that "Israel held massive military superiority over Egypt".
You're not reading what they're writing. They all were predicting a rapid Israeli victory, within mere days. They believed that Israel could take on all the Arab states at once and still win.
If you want a more colloquial version of the US assessment, this is what Lyndon Johnson told the Israelis before the war (paraphrased in the official US diplomatic records):
“The US assessment does not agree with that of the Israelis: our best judgment is that no military attack on Israel is imminent, and, moreover, if Israel is attacked, our judgment is that the Israelis would lick them.”
