Though isn't the First Contact scenario different? I mean, it would not be their own timetravel event that makes their universe impossible. Augh.

I suppose I just have to assume that there is something in the ST universe(s) that causes the overall gestalt of events to stay similar and makes sure that things stay internally consistent as the inhabitants perceive it, in that certain connected events change in tandem across times and then the overall timeline of the AOS universe might align itself somehow.