[belorn]

> who would decide which of Numenta's patents are assigned by the GPLv3 and which are not?

The GPL text is rather precise in how to determine which patents are effected. Any patents that would be infringed by some manner of using, making, (...), or modify that specific version of the program is covered by the license.

As far as patent grants goes, it is hard to make something cover beyond that. I guess a license could say "you may not own any patents, and that is the final word", but I do not know any licenses that does that.