On re-reading that other guys comments, they just make no sense. You are right to draw your distinction, because this thread is being strangely vague on details and trying to encourage conspiratorial thinking without specifics.

That said, I think the core concern can be rephrased in a way that gets at the essence, and to me there's still a live issue that's not relieved simply by noting that this requires probable cause.

What's necessary to establish probable cause in the United States has been dramatically watered down to the point that it's a real time, discretionary judgment of a police officer, so in that respect it is not particularly reassuring. It can be challenged after the fact in court, but it's nevertheless dramatically watered down as a protection. And secondly, I don't think any of this hinges on probable cause to begin with, because this is about the slow creep normalization of surveillance which involves changes to what's encompassed within probable cause itself. The fact that probable cause now encompasses this new capability to compel biometric login is chilling even when you account for probable cause.

And moreover, I think there's a bigger thematic point here about a slow encroach of surveillance in special cases that eventually become ubiquitous (the manhunt for the midtown shooter revealed that practically anyone in NYC is likely to have their face scanned, and it was a slow-creep process that got to that point), or allow the mixing and matching of capabilities in ways that clearly seem to violate privacy.

Another related point, or perhaps different way of saying the same thing above, is that this should be understood as an escalation due to the precedent setting nature of it, which sets the stage for considering new contexts where, by analogy to this one, compelled biometric login can be regarded as precedented and extensions of the power are considered acceptable. Whatever the next context is where compelled biometric login is considered, it will at that point no longer be a new idea without precedent.