That's an unproven allegation. Navalny was actually poisoned.
These were claims made in court, during formal hearings. They weren’t disputed, and as such, they are part of the official court record and are worth more than random hearsay.
The US’ repsponse (as quoted) was that these allegations were “wholly irrelevant.” That doesn’t sound like a denunciation or denial to me.
Anybody can make claims in court and the US government is hardly going to confirm or deny poisoning someone.
It's an unproven allegation and a world away from Navalny who was actually poisoned.
Why would the US government not deny poisoning someone?
I know HN loves Assange but comparing an unsubstantiated stamenent that US persons talked about extreme measures, vs actual poisoning is pretty weak.