What are the IRS's "unforeseeable events"?

IRS Pub 523 lists five unforeseeable events and then leaves the the door open for more by saying "An event is determined to be an unforeseeable event in IRS published guidance." Where can I find this guidance?

 

We moved across the street from our kids in 2021 because my husband has Parkinson's Disease and we are 80 and 73. They had no intention of moving at that time, but a wonderful job has landed in my daughter-in-law's lap, and they are moving states away. We will follow them since there's no family left here. We can't really wait out the 2 years and make the move by ourselves.

 

Would the IRS accept this as an unforeseeable event?