[suddenlybananas]

Have you considered that people may join HackerNews who were not already on it?

[QuantumNomad_]

And in particular, people might lurk for a long time without an account until one day a thread makes them want to comment so much that they go ahead and create an account to comment.

Although, the username they picked in this case does seem a bit specific to the topic of the single comment they wrote. So it remains to be seen if this particular case was a throwaway account only used once, or if they will keep it.

[freedomben]

Also usernames/handles can be surprisingly hard. It seems reasonable to me that people would pick something related to what they are thinking about at the time.

[izacus]

What's way more likely is that they've created a sock puppet account though.

[testdelacc1]

Have you considered googling what a sock puppet is?

See, both of us can make comments in that same condescending style, pretending to be polite.