What does sole survivor mean?

The other day, I had to ask myself, "What does 'sole survivor' mean?"  I always assumed it meant there was only ONE survivor in an accident or disaster.  I looked it up and got this answer:

The term "sole survivor" refers to a person who is the only one to live through a disaster, accident, or other event where many others died.  It can also be used more broadly to describe the only remaining member of a group or the only one of its kind.

Now I'll tell you why I'm looking up something so obvious to most of us.  Two people survived a boating accident on Lake Tahoe recently, and the headlines (HERE:  https://www.yahoo.com/news/sole-survivors-lake-tahoe-boating-204221207.html) said:

Sole survivors in Lake Tahoe boating accident had one thing in common.

Two survivors?  Then there is no "sole" survivor.  There are TWO, not ONE.  Whoever wrote that article needs to take a refresher English class.

Oh, you want to know what those TWO people had in common?  They were wearing life jackets.