Marvin said-
The issue you cite of not knowing whether the numbers of JWs with blood disorders even in similar countries (e.g., Australia) are the same, let alone in very different countries (e.g., Ghana) is a factor to consider, and I did consider this in my assessment. My finding was that there is no reason to think mortality due to severe anemia patients (for all causes) refusing blood was more prevalent in New Zealand than any other nation. Hence to use these New Zealand values is not to overstate what we should expect overall (the world). For this reason my extrapolation is conservative.
Your statement (in bold) is eerily reminisent of an 'appeal to ignorance' argument, AKA "lack of evidence to the contrary".
From Wikipedia on "Argument from Ignorance":
It asserts that a proposition is true because it has not yet been proven false (or vice versa). This represents a type of false dichotomy in that it excludes a third option, which is that there is insufficient investigation and therefore insufficient information to prove the proposition satisfactorily to be either true or false.
You're also "begging the question" (simply repeating the very question at stake, without presenting any supportive evidence) and engaging in "special pleading", as if you don't have to present supportiive evidence for YOUR UNVALIDATED CLAIM that it is appropriate to extrapolate from the clinical data to apply it Worldwide.
Adam