You need to reread what the actual contention is. Arguing from the negative is not essentially faulty but how you use it and what it means can be faulty. Let me use a parallel example regarding skepticism.
Sorry I just wanted to bold 2 statements so you see them together.Ã‚Â I know this is a rather blatant use of quote mining.Ã‚Â Sometimes people don't realize when they have a cognitive dissonance.Ã‚Â You allow Creationism to argue for the negative, but do not allow Atheists the same arguments.
This is one of the best quotes regarding a solution to how one should approach the use of skepticism:
"While skepticism is not defensible as an epistemological position, it is of value. It acts like a burr in the epistemologist's saddle, demanding that any claim to knowledge is based upon adequate evidence and is free from contradiction and absurdity."
Many arguments between skeptics and Christians may give the impression that a Christian could fundamentally disagree with skepticism (which I would contest as unreasonable). Also the position of skepticism and arguing from the negative have essentially the same perspective. While a person is being skeptical about something there is no logical demand that an alternative needs to be offered, it is sufficient to demonstrate that a position is ridiculous based on its own merit without even offering a solution to fill its place.
Here is the sticky part and the thing that turns a rational activity (skepticism) into an irrational foundation (being a skeptic). Just like skepticism, atheism can not supply an epistemological foundation because it makes no positive claims. So when someone says they are fundamentally an atheist or a skeptic they are entering an irrational mode, just as much as it would be irrational for me to say that my basic worldview is as an anti-evolutionist.
Do you see the difference yet? If not answer this question; How would you react if I told you that my basic worldview was anti-evolutionist? Would you think it is rational to build my basic foundation of reality off of the initial belief that evolution isn't true (which, by nature, is arguing from the negative)? While I certainly believe that evolution isn't true, don't I have to find something else to start with to stake a claim to what the nature of reality actually is (a positive argument for why things are the way they are)?