Where is the logic here?

What are we to make of the following?

Writes Dembski:

I argue that the explantory filter is a reliable criterion for detecting design. Alternatively, I argue that the Explanatory Filter successfully avoids false positives. Thus whenever the Explanatory Filter attributes design, it does so correctly.

Writes Behe:

To falsify design theory a scientist need only experimentally demonstrate that a bacterial flagellum, or any other comparably complex system, could arise by natural selection. If that happened I would conclude that neither flagella nor any system of similar or lesser complexity had to have been designed. In short, biochemical design would be neatly disproved.

From "Debating Design" by Dembski and Ruse:

More generally, Dembski (1999, 2002) has argues that irreducible complexity is only a special case of complex specified information (CSI)...

Dembski's explanatoty filter yields no false positives.
The explanatory filter detects design by measuring CSI (complex specified information).
IC (irreducible complexity) is a special case of CSI.
The identification of an IC structure should, then, also yield no false positives.
If there was an IC structure found that could form in the absense of intelligence, then only more "complex" structures would be considered irreducibly complex.
But that would entail that the first IC structure that turned out to not be IC was a false positive. So, the explanatory filter, while yielding no false positives, is quite happy to accomodate false positives. Go figure.