You are conflating two completely different quantum levels of conspiracy theory. Science fiction vs science fact.
The difference here being that we have proven that this exact kind of skullduggery exists, because we've seen similar attacks performed by our own alphabet soup agencies, and concrete proof thereof.
The difference here is not substance, but choice of vector. A COMPLETELY different level of "What If?"
[EDIT]
I was really hoping that these guys, who work directly with the kinds of manufacturing involved, could lay down some meager reassurance that there was some level of security at this level of production. Of course, they probably don't work with the specific factory in question, so still a case of "Absence of proof ≠ proof of absence"; even as horrifying a picture as they paint of that supply chain in general, it's still POSSIBLE that the particular factory SuperMicro contracted with actually has some reasonable physical security in place.
[/EDIT]
Cheers,
mnem