I don't think the insulin "knows" there was a power outage. What it "knows" probably, is that it was at a high temperature for an extended period.
If the insulin got warm (say over 90 degrees for weeks) then its lifetime may have been affected. The "28 day rule" is I think based on lifetime of 28 days at warm, out of the refrigerator, temperatures.
3 days into a power outage, the inside of the fridge is definitely getting warm, close but maybe still below room temperature. I don't think 2 days at room temperature spoils the insulin.
In the past when we had extended power outages in the winter, I could just usually move my insulin and other fridge items to a part of the house that wasn't below freezing. In some cases all the house was like at 35 or 40 degrees (I'm thinking the icestorm of Feb 1999, lost power for two weeks.) It's a lot harder in the summertime.