Apparently Schreier didn't get it either.
Apparently not.
I have a good friend with a much more extensive reference library than I have, I expect to be seeing him this weekend and will do some research. Will be interesting to see what some other "noted authors and historians" have said, in reference to the 4 points you listed.
Thank you for taking the points out of context for brevity, and I hope we can avoid errors in understanding, because of that.
My personal response to those points, (going strictly from memory, and my understanding of what he said) is.
The first two, where he uses "complete mystery" and "very puzzling" indicate the author's
opinion, about facts he apparently does not have.
Commonly "known" history is often somewhat at odds with verifiable actual history, so I'll be doing some research for actual verifiable facts.
Legend has it that the caliber choice was either a military requirement, or was Winchester idea, accepted by the military. I'll see if I can find any proof, either way.
#2 and #3, commenting on "puzzling in light of previous US Army knowledge and experience" and "adopted without any developmental testing to speak of, and this is very unusual in the US Army", can, I think be explained by the fact that there was a war on, and the Army, being under just a bit of pressure, departed from their usual peacetime practices for procuring arms.
Again, I shall look for verifiable references.
#4, commenting again on the caliber, " the biggest single deficiency in the carbine--it's ammunitions's ineffectiveness" is arguable, depending on two main points, #1 what the carbine's "single biggest deficiency" actually is, and #2 what definition of "ineffectiveness" should properly be applied to the ammunition.
Both the effectiveness, and lack of same from .30 carbine ammo are legendary. Legend is often an embellishment of the actual fact both ways.