The very act of clarifying that uncertainty is not insubstantial (and I don't mean to suggest that it's not worth doing…sorry for the quadruple negative there, albeit intentional). Obdurate* suggests some sort of stubborn refusal, and I really don't think that's the case. @milesmcbain pointed to an rOpenSci working group in the ggvis thread, which can hopefully help bring clarification, in the absence of any sort of "resolution." That's not intended as a brush off— there's a lot of overlap between RStudio and rOpenSci, and (true to OSS-form) these conversations are kind of inherently a part of the evolution.
* Stephen King uses the word to describe "the past" seemingly hundreds of times over the course of 11/22/63, and I'll never be able to think of the word in the same way again.