Probably "wrong" here should be in scare quotes. It's not the wrong year; it does return the correct ISO year. It's just that ISO year is not what you want so you should be using %y rather than %g.
Check the actual link: that's exactly what the email linked to says. (And the title here is simply the title of the email.)
I'm assuming that (1) the poster is warning others about this or (2) he finds it amusing that the response to "The year is wrong" is (roughly) "No, that's how the standard defines year. The output is right relative to that standard. Dates and times suck." (the last sentence is implied) or (3) both.
