Buried in the google drive is a note that this does not remove the need for brushing teeth, but it just notes that not doing that will give you bad breath.

In fact I believe that this is the true cause of this not being a product - people will still need to brush their teeth for other reasons than preventing cavities. If brushing teeth correctly currently lessens the risk of both caries and periodontal disease, having a shot that removes the risk of caries could conceivably mean less conscientious tooth care, which increases the risk of gum problems.