Perhaps I should have said "target customers" where I said "customers", I don't know. But it should not be surprising that "being an HN user" correlates strongly with "finds out about things on HN".
I think that statement is generally true for any random company, but I think for a company like Kagi, HN users are actually a lot more representative of their user base.
...and to be clear, Hacker News is not a representative sample of their customers.