It seems to me that "flushing the pipes" in this manner would only affect the amount of lead due to joints within the house. It wouldn't hide a problem with the municipal water supply. So if not flushing causes the test to go over, the implied fix is for the owner to replumb (deplumb?) their house.

It would be nice if the article spent some time detailing the mechanics at work and resulting implications, rather than only touching upon the actual specifics once, spending most of the article beating around the bush with tangentially-related scare stories.