They give several well-considered criticisms of the question - it leads people to focus on socioecomonic status, it doesn't correlate with other measure like whether they report experiencing joy recently, etc. It's not much of a defense to simply say "well, it's the standard".
Is joy related to happiness, or are they two separate concepts? That depends on your cultural background and the languages you speak.
The World Happiness Report can be traced back to the UN General Assembly Resolution 65/309, which was proposed by Bhutan. Therefore the intended definition of happiness in this context is similar to the one in Bhutan's Gross National Happiness index.
My criticism is about how the dramatic language differs from the banal content of the article.
Titling it "The World Happiness Report Is a Sham" and calling it "beset with methodological problems", I would expect some more serious scientific malpractices, like data fabrication, calculation errors, sampling problems, p-hacking, etc., not "I think there are some problems with this variable".