Except if one is going to handwave away historical reality without
TFSmith121 is agin' it. Methinks there must be something to it
Joking aside, let's see where Abe wants to go with this before deciding it is a stretch. Lots of guys above the Guam commander's pay grade dropped the ball Dec7/8 OTL. How many pages would you run to of all the things that happened in WWII that would make Turtledove credible if they were fictional events?
Except if one is going to handwave away historical reality without any explanation - and for my money, it doesn't matter whether its "why is a professional O-6 forgetting the basic responsibility of an officer about to surrender his post" or "why is it (for example) an air arm that did exceedingly well historically (the IJNAF, perhaps) suddenly unable to accomplish what it did in reality."
One is putting one's thumb on the scales, so to speak, and handwavium is handwavium; bring on the dragons and the time travelers with submachine guns - it's really just a matter of degree.
Suspension of disbelief is one thing; making a known real-life individual "do" something atypical is like breaking the fourth wall.
Here's Capt. McMillin's report, by the way; based on this, seems like thorough, professional, and quite humane individual: