Logic dictates that timeline branching happened when Sphere-bulders got the Xindi to attack Earth, and that's the timeline Nero's (Spock's) wormhole led to, not the one TOS took place in.
Unless, from TOS' perspective, those changes were always a part of history. After all, there was no big Delphic Expanse in TOS or TNG. Why? The NX-01 crew ended it.