Contradictory Arguments

I found this comment on the web page at http://preview.tinyurl.com/q4q3xl:

"On the one hand people point to various complex structures and assert that there is no way to explain something so magnificent by reference to gradual accretion. But when a scientist then comes up with a plausible, step-by-step account for how the structure could have formed, suddenly the criticism is that you can come up with a story to explain anything."

After debating a creationist for the last few days who made both of these points, I realized that those arguments do, indeed, contradict each other.

His primary claim was that things like the complexity of DNA was impossible to explain without having an Intelligent Designer. But he also argued that the fact that scientists could provide interpretations for everything in the fossil record didn't mean anything.

You can't have it both ways. If science can provide an explanation, then you don't need an intelligent designer to explain it.