I think it's more the keming of the domain portion of the HN title, especially combined with HN's rather small font size choice (it's a meager 8pt¹!) there, and that it just happens that the mis-kemed result ends up with "John Mastodon", and is thus not trivially noticeable as "wrong"…

(I read it the same way, too.)

(¹I personally have a browser override for HN's tiny font choice; I thought that 12pt was the universally agreed upon "base text" point size, and "10pt" was "small text", but HN's "normal" is 9pt.)

Dyslexics of the world, untie!