My first question was "why an exponential curve?" But, well, I can understand it in the context of "it's rational to think things are generally consistent throughout history" with what we know of measurements and repeatability and all that. Therefore, the exponential curve is signifying how "crazy" things can get as you get further and further away from our "rational" expectations.
So, the exponential curve does make sense to me.
But... I don't think the argument will have much of an impact on those you would intend to use it for... They seem to believe that history was not anything we're used to or anything close to what our "rational analysis" would lead us to conceptualize. They have no issues with dismissing the evidence.
Taking that sort of position into account... I don't see this "additional rational exercise" being helpful in trying to show a creationist the error of their ways. It seems like the rebuttal would just be another "tree rings worked differently then!!!" kind of denial...
Might be helpful for some of those who are newly on the fence about the subject and just trying to gather more information, though?