I agree, I think there are many more issues to consider. However, the OP seemed to be focusing on that particular argument, hence my comment. A few examples:
"The results were that the people using the dynamic version of the language got stuff done much quicker"
"it took less time to find those errors [in the statically typed language] than it did to write the type safe code in the first place [in the dynamically typed language]."
"[programs written in]" dynamic languages took significantly less effort to create (less time)"
