You kind of lost the thread when you say, “act against the interests of American citizens and companies”. Bro, literally anyone could be using xz, and anyone could be using Red Hat. You’re only “acting against Americans” if you use it against Americans. I don’t know who was behind this, but a perfectly plausible scenario would be the NSA putting the backdoor in with an ostensibly Chinese login and then activating on machines hosted and controlled by people outside of the US.
Focusing on a specific distro is myopic. Red Hat is popular.