Thanks for the recommendations! Did you mean something specific when you referred to "Bostock's notes", or did you just mean his various blog posts and papers?
Turns out Bostock explicitly avoided devising Yet Another Grammar of Graphics in favor of selection and transformation operators. Which, as it happens, is a very sparse but expressive grammar anyways (cf dplyr and other corners of the Hadleyverse). Nonetheless, I misrepresented his idea of maximizing expressivity by minimizing grammatical constraints.
The IEEE paper is even better than I remembered. It's just as good today as it was when he first submitted it.