I agree with you on this perspective, and I've used this argument before too. But, thinking about it now, I don't know this is really a useful argument, since, on the population scale, a mutation is essentially defined as an increase in information. Obviously, this isn't what creationists object to at all.
I think it's vital that we emphasize that what creationists object to is based entirely on a strawman version of evolution. In this line of argument, they are ignoring how evolution actually works. As I said at the outset, I agree with what others have said. But at bottom, it's irrelevant whether a particular mutation increases or decreases "information" because it's indisputable that mutations do increase "information" in the population overall.
By all means, show that the creationist claim that mutations decrease "information" is bollocks. But that demonstration is rather technical, and includes difficult discussions about what "information" means and how to measure it. For the uneducated, it's all a lot of muddy water. By contrast, the demonstration that every mutation increases "information," no matter how it's defined, is clear to even those who know absolutely nothing about genetics. A mutation creates a new genetic sequence that wasn't present in the population before the mutation occurred, but doesn't eliminate the sequence that existed before the mutation from the population. Ergo, more "information."
Ridicule is the only weapon which can be used against unintelligible propositions. -- Thomas Jefferson
We see monsters where science shows us windmills. -- Phat
It has always struck me as odd that fundies devote so much time and effort into trying to find a naturalistic explanation for their mythical flood, while looking for magical explanations for things that actually happened. -- Dr. Adequate
...creationists have a great way to detect fraud and it doesn't take 8 or 40 years or even a scientific degree to spot the fraud--'if it disagrees with the bible then it is wrong'.... -- archaeologist