Pardon me, but depending on the question, both theories about whatever it is could very well be wrong, or both could be partially right. Life is very rarely so neat and clean as to present you with exactly two possible answers, one absolutely right, and the other absolutely wrong. ;)
At first, the quote did not seem to be logicly supportable and you pointed out the obvious flaw; and you could be correct.
On the other hand, that logic may not apply to the macro-evolution v. intelligent design/special creation debate. The positions are so diametrically opposed that it is impossible to reconcile, or synthesize these opposing positions into one conclusion without utterly refuting both sides. While man cannot fully comprehend the designer and his methods, one can still readily support the conclusion that there is a creator.
Also, since in this debate no one has prososed a scientific model other than macro-evolution or creation/intelligent design, it is logical to conclude in this case that one must be true and the other false. This being this situation we find ourselves in, if one of the positions can be demonstrated to be false based on science and the observable evidence, the opposite position must be true.
Can this be determined with absolute certainty. Probably not. Can it be determined to the point where one might risk his very life and soul on it? Absolutely, because I have done it!
Evolutionists are so eager to point out that those who believe in the God of the Bible base their belief in a Creator soley on faith unsupported by evidence, yet those same evolutionists base their faith in evolution on mere speculation and suppositions which they claim to be facts. Merely stating that macro-evolution is a fact just because one makes the claim is no different than claiming that black is white. The truth stands on its own, and does not change merely on the whim of a man.
If you haven't done so yet, you might want to read the excerpt of Popper's essay at post #47. Perhaps you will agree with me that the very things which disturbed Popper about Marx and Freud are the things which are troubling to many people today about Darwin.
Hugs!