I'm not unaware of the 1918 pandemic. I've almost read Barry's book a few times now. ;-) I certainly haven't done the research you have but I would argue that the treatise above indicates that there are several compelling theories as to the start of the outbreak but no consensus view.
When I was born, scientific consensus had just shifted to "comets" wiping out the dinosaurs. As I grew up it wavered between volcanism and maybe a meteor or comets or something. By the time I was in middle school everyone was focusing on the K-T boundary and when I was in high school it was "Mr. Plum in the conservatory with the iron pipe." As such, I might be a little more sensitive to stating things are settled when in fact, they aren't. After all, Weekly Reader told me in no uncertain terms that the dinosaurs were wiped out by a supernova, which served to make an entire generation of schoolchildren afraid of the stars.
Some concluded it started in China or European trenches. However, the CDC and other authoritative sources report that the influenza epidemic actually began in the US spreading to Europe as US troops deployed and later to Asia.
The CDC (your link):
Confounding definite assignment of a geographic point of origin, the 1918 pandemic spread more or less simultaneously in 3 distinct waves during an ≈12-month period in 1918–1919, in Europe, Asia, and North America (the first wave was best described in the United States in March 1918). Historical and epidemiologic data are inadequate to identify the geographic origin of the virus, and recent phylogenetic analysis of the 1918 viral genome does not place the virus in any geographic context.
That you're bringing up meteors now that we're actually talking about it reinforces my notion that perhaps your statement shouldn't have been so definitive.