Guido’s proposing a moratorium on changes to the Python language, the idea being to enable alternative implementations to have a stable target to aim at. This only applies to the syntax of the language, not to the stdlib, nor to the underlying implementation: the announcement hints at acceptance for a GIL-free implementation if one came along.
I’m all for it, myself. Like other people, I believe that the stdlib needs lots of care and attention in several respects. Removing one focus of changes will result in at least some of that effort shifting to the stdlib. (Altho’ it will probably result in some of the effort simply going elsewhere :) ).