We shouldn't rule out the probability that this account is from a U.S. agency as well.
This is more reckless than any backdoor I can think of by a US agency . NSA backdoored Dual EC DRBG, which was extremely reckless, but this makes that look careful and that was the Zenith of NSA recklessness. The attackers here straight up just cowboy'd the joint. I can't think of any instance in which US intelligence used sock puppets on public forums and mailinglists to encourage deployment of the backdoored software and I maintain a list of NSA backdoors: https://www.ethanheilman.com/x/12/index.html
It just doesn't seem like their style.
Operation Northwoods came about because Brig. Gen. Edward Lansdale, asked the CIA to come up with a list of pretexts that might be used to justify an invasion of Cuba. This request had a number of planners at the CIA enumerate possible false flags that could be used as a pretext. One of those plans was a terror attack against US citizens. Operation Northwoods was rejected and never implemented.
The US has plans for nearly everything, but there is a massive difference between a plan that some CIA analyst is pitching and something the US is likely or even able to do. The US had all sorts of plans for how to handle a pandemic, but then when one actually happened, the plans couldn't be implemented because the US didn't actually have the capabilities the plans called for.
> example, perhaps they were planning to blame the hack of a power plant or critical infrastructure on this exploit, then use the "evidence" that was leaked to prove it was China, and from there carry out an offensive operation against Chinese infrastructure.
Backdooring OpenSSH would in no way function as a pretext for attacks on Chinese infrastructure. No one outside the tech companies cares about this. The US also doesn't need to invent hacking pretexts, you could just point to one of many exposed Chinese hacking incidents.
And if someone wanted to attack a target running on Loongson, they would certainly have to make sure the code can actually run there in the first place.