There was another time, not long ago, when people justified doing or facilitating vile things against masses of fellow humans as “just following orders”.

Their point is valid—refusing might cost own life, and there's the prisoner's dilemma, etc. A situation like that seems unlikely to be resolved from within a system itself.

However, appeals to consequences aside, in the end each of us has a choice: write that code (slash architect that solution) or not.

There are a lot of people who have never faced the decision “Do I stand up for what’s right when it means my family will be murdered?”. While you’re clearly familiar with another scenario where that happened, others aren’t, and so the parent comment may help them realize that.

We don’t have evidence that the latter engineer was actually facing a choice between implementing the feature and non-figuratively sacrificing their and their family’s life. Unlike the 70+ year old precedent I was alluding to, for a talented software engineer of non-Uyghur descent in competitive modern China forever robbing yourself and everyone from your family of the opportunity to advance up the party hierarchy may well qualify as “very huge consequences”—meanwhile, what the feature in question facilitates may well qualify as a crime under international law.

Everyone may have the choice but for some it's easier to say no than for others..

Since it’s posted here on HN, I believe this is primarily addressed to those whom saying “no” would cost maybe a promotion, a customer, or even just impaired relationship with a manager.

Having to choose between your family and thousands of others is tragic and I can’t honestly claim which I’d choose, but being blind to that choice (intentionally or not) is probably even more tragic.

Unfortunately I doubt fear of reprisal was the motivating factor behind whoever wrote this code.

Perhaps. But I'm appealing to HN readers here, not to China.