[citation][nom]emperor piehead[/nom]Its not, its a full water loop kit which means everything you need for one and usually at a cheaper price than the individual parts. Also it doesn't say anywhere this is an AIO.[/citation]
As you say, they don't call it an 'all-in-one' but states it is for people looking for an 'all-in-one'. As in this is the closest you can get because of the customisation that is needed for water cooling. And it is only for your CPU.
DarkSable saw the 'all-in-one' and is probably complaining about the lack of a GPU block.