AI will explain it, but it's against HN rules for me to post the explanation.

Basically they are misleading when they say "thermal equilibrium", same physical temperature does not imply thermal equilibrium.

FWIW, the "Significance" blurb at the very top says as much:

> An interesting feature of the system is that all components of the system are at the same physical temperature, but it functions because they have different noise temperatures.

(I assume it's not AI-generated.)

Thanks for not being a fuckwad who just copies an AI answer. I appreciate you understanding it and putting it in your own words.