

I believe the time line was altered by the events that transpired in the TV series Enterprise. So it is safe to conclude that both Spock and Nero were products of an already previously altered reality prior to entering into the time line of he movie thereby altering that already altered time line. It however does resemble the Enterprise of TMP, post TOS era.

Look at the design of the Kelvin and you can see that it does not resemble in any way the Enterprise of TOS era, or prior. The ship design was TMP (Trek Movie Picture)era although it was being used in pre-TOS (Trek Original Series) era.

It is safe to say that the time line was already an altered one given the evidence at hand.
