This is not needed under the inference system proposed in that paper.

> But then I decided I wanted to live in a world where people don't need to write a Ph.D. thesis with a hundred pages of footnotes covering every conceivable logically-possible eventuality just to make a simple point.

Have you considered finding better examples instead? I think that a better explanation on the differences between static and dynamic typing would be to simply say that in dynamic typing type checking happens during the runtime while in static typing type checking happens during the compile time.