Huh?? What the...?
No one claims that design isn't possible. Where you got that from is simply beyond me.
That something (well, just about anything) could have been designed by an unknown designer with unknown abilities resp. limitations and the right motivation, is trivially true and no one denies that but it's equally worthless as a scientific explanation.
What you said! :)
That's true -- no one claims it isn't possible. Until, that is, it's put forth as a hypothesis. And then it becomes, somehow, a "non-scientific" position. And therein lies the complaint: that the unarguable validity of the hypothesis is dismissed out of hand.
Verification of the hypothesis is, of course, another matter. However, the "anti-ID claim" is that, essentially, it would be impossible to detect design. Perhaps -- or perhaps not -- but the claim itself is completely unscientific: is it really impossible to detect it, or merely rhetorically convenient to make the claim?
The fact, however, is that design is a perfectly valid hypothesis, precisely because it has been demonstrated.