Orci and Kurtzman argue the opposite with basically the line that if Tasha Yar remains to exist post rift closure and if the alternate 24th century had ceased to exist that she would also.
Yesterday's Enterprise kinda disproves the parallel universe theory, doesn't it? At least for Guinan.
I thought that it was explicitly stated that the JJverse exists in parallel, to the Prime universe, actually the law of the multiverse would create multiple prime universes at the point Nero A left the prime universe a number of these would be universes where he never got anywhere near a temporal event(I assuming the Kelvin) to destabilize the timeline and threaten the Prime universe existence.
How would he return to the prime universe? The universe he's just helped create has overwritten it.
^The above is basically taken from quotes from Orci and Kurtzman who like to reference Yesterdays Enterprise however they infer that the Enterprise C 24th century would continue to exist post its entering the rift which is not what we see on screen as its replaced with the regular prime universe. It is indeed something that is debated but never conclusively proven either way. Alternate Picard ultimately thinks that its worth sacrificing both Enterprises for.