It's a joke product sold as an empty can by some emergency supply stores for April Fools or white elephant gifts. But, that never stopped anybody from wondering how to make it real.
Presumably it would be delivered in tablet form, to which you could just add water to dissolve it.
I see you ignored the second sentence of the post. Try reading it, it answers your question.
No, it just states a scientific sounding premise for the idea, but it doesn't make the concept any less absurd.
The idea of trapping water is not absurd. The name is intentionally absurd as a joke. The joke name is explicitly overruled by the description. All you need is a chemical that holds water in some manner and releases it in the presence of a catalyst. How is that concept absurd?
Hydrous compounds have existed for ever, but that doesn't mean they're "dry water."