The "yes" scam has been around for years (maybe like 4). For all the hoopla over this "yes" scam, I have yet to hear of any confirmed documented case(s) of fraud taking place due to just a "yes".
It pays to be cautious, but don't go overboard.
Should you happen to say "yes", do not loose any sleep over it. I'd keep an eye on things...like I am sure you normally do.
Some people like this poster ( the alleged "Police Officer that hates these calls") want to spread fear and panic. Don't fall for it.
You know if you just do not answer unknown calls you won't have to worry about saying yes or no.
(FYI...in my experience, real police tend to keep their titles low key and not brag about who they are or what they do)