Unfortunately, falsifiable does not mean false. Putting that argument is simply leaving the issue open to creationists to claim some credibility. They're experts when it comes to that: God is always placed deliberately beyond science so that his existence cannot be refuted by evidence and reason. The case against intelligent design is that, in the 21st century, it is an argument from a position of deliberate, eyes-shut ignorance. Classic God of the Gaps stuff (though its supporters never actually see the gaps closing fast). In 1859 Darwin anticipated intelligent design (a move that was sine qua non for his theory) and refuted it beautifully in Chapter 6. We have far more evidence today, much of it in the fields of genetics and biochemistry, than Darwin couldn't even dream of having, and there is no excuse for putting an argument that ignores it, let alone ignoring all the excellent work done which comprehensively debunks the notion of a designer. What a shame that supporters of intelligent design deliberately display a lack of the main attribute of their proposed designer: intelligence. You can't argue with idiots. Well, it can be fun to try.