Do you grasp the difference between identifying the DNA of individual human beings and between virii and human beings, squash, and bacteria? Using PCR in paternity tests is not specifying that the DNA is human or not. It is based on the assumption the DNA is human.
It cannot be used to ascertain if the DNA is from a human being or not. It can only amplify extant material, not specify the source of that material. Means of specifying the source of material have been developed, and Koch's Postulate is how that determination is made.
Of course PCR only multiplies the genetic material. So what? You think we can tell two humans apart from each other by DNA, but we can't differ between different virus strings?
You're missing the point: the tests don't specify the virus at all.
PCR cannot do that.
The test is claimed to do what it cannot do. It is not a test for SARS-CoV-2. It just amplifies sequences. A test for a viral infection must detect a virus, which PCR is incapable of doing.
It's like claiming the DEQ tests detects cars. It doesn't do that at all, and using DEQ testing to prove it's being used on cars cannot prove it's being used on cars. The DEQ measures specific particulates in exhaust fumes, which can come from a variety of sources, such as trains, planes and automobiles.
Tests to detect viruses can be made, and the PCR test isn't one.