This reminds me of an argument I had with a believer who insisted that his god must have "guided" evolution to create life as we know it.
I pointed out some examples of poor design, including the panda's thumb, probably the most famous example:
Our text books like to illustrate evolution with examples of optimal design--nearly perfect mimicry of a dead leaf by a butterfly or of a poisonous species by a palatable relative: But ideal design is a lousy argument for evolution, for it mimics the postulated action of an omnipotent creator. Odd arrangements and funny solutions are the proof of evolution--paths that a sensible God would never tread but that a natural process, constrained by history, follows perforce.
"Well," my friend explained, "God doesn't care about animals, only about people."
So I pointed out some examples of poor design in human beings. His reply? "God didn't want us to be perfect." Heh, heh.
This was a guy who claimed that he'd researched "all" the major religions and came by his faith objectively. It was just a coincidence, apparently, that the religion he'd been raised to believe just happened to be the right one!
His belief in Intelligent Design was similar. He already knew what he wanted to believe, so he just rationalized away any contradictory evidence. And note that he had no evidence of his own to back up Intelligent Design. No, he didn't need evidence. He just believed it.
Unfortunately, you can't reason a person out of a position they didn't reason themselves into. He didn't believe in Intelligent Design because of the evidence backing it up,... because there isn't any. So evidence against it didn't affect his belief in the slightest.
And that's common among human beings. In fact, I'd say that's a great example of poor design (of human brains) right there! We find it easy to believe what we want to believe. And when you don't require evidence - real evidence - for your beliefs, it's even easier.