Don't blame the test - it is what it is*. Instead blame the police department that deployed this test and either didn't properly educate the officers administering it or actively mislead them.
The very idea that someone who - by the nature of the test administered - is only potentially in possession of an illicit substance can have their face and details splashed around as though the evidence was in is indicative of gross negligence on behalf of the police force.
And negligence is the more generous judgement, for if it is not negligence then it is a wholesale abandonment of their responsibility to exercise their vast powers over the citizenry with care and restraint, and to be ever mindful that they uphold due process and the rule of law.
The police, in this instance, prioritised public self-congratulation over their responsibility to protect a private citizen. In their self-righteous haste they negatively impacted the reputation of a thoroughly innocent civilian.
While there was clearly grounds for suspicion here - the initial, basic test was positive - this incident nevertheless shows that the police, institutionally, rate the rights of innocent civilians very low indeed.
In fact, given that this person posed no danger - he was not found with a weapon or a stolen car or acting suspiciously around a school or in a domestic dispute - the eagerness of the police to crow first and check later is all the more telling.
* - And I am sure the limitations of it were adequately conveyed to the department when it was being purchased.