It's already out there. You don't need to ask.

It’s considerate, polite, to ask instead of assuming the author would be ok with that

I find it weird, not polite, personally. Polite would be to not bother them and just use it anyway without drawing their attention to yourself unnecessarily.

Different norms, perhaps.

Why would you assume they would be bothered? They are actively discussing with us all on an open forum. And can just ignore if they don’t want to engage

I didn't assume they would be bothered. I view asking them as performatively seeking attention and therefore bothersome. It's a norm about the general situation not a prediction about the individual one.

The author has published on the topic and engaged in conversations on HN about the topic.

They're clearly ok with the topic being discussed and shared.

Consider that many people do things that they don't need to do!