Dale Sams wrote:
edit: Now granted, Spock may not be aware of these new rules...how could anyone? Unless there are some differences he may have discovered.
Spock knows that the correction he made in "Yesteryear" (TAS) resulted in a similar, but not total, restoration of the timeline. His pet Sehlat now dies much earlier that before, but the death of a pet was not deemed of concern to all, so the timeline was left different.