Occam’s razor is that they’re doing what they say they’re doing and not some more complicated future action.
You said earlier upthread, that HN is ignoring the tradeoffs. I find that distasteful, people have considered the tradeoffs of this and they don't like them, but that doesn't mean they need to preface every single statement about the thing with "well actually i've considered the tradeoffs, and I've found them to be blah, and..." That would quickly get tiresome which is why people don't do it.
I'll make a different, similar generalization. Like most people pushing this, you are pretending to care about the "tradeoffs", but you don't. You don't care about the downsides, you just say you do, and then blithely ignore them when they are brought up. What's the golden rule again?
I don’t know enough about the specific implementation or perceptual hashing details and probably pushed back too hard as a result of the other comments at the time (which were comments out of ignorance).
The level of downvotes I received is disproportionate to what I wrote anyway - this is clearly a political issue on HN. The irony is I’d probably align more with the risks being too high position, but it needs to be considered after actually understanding what the true risks are first.