"NOBODY better decide to take it on themselves to tell MY children otherwise.
"
Nobody? What about little Billy? He's in your kid's class, and he KNOWS that Santa is a "pretend" character. What will you do when Billy tells your precious little one? Go beat him up?
No kid gets through Christmas in 1st Grade in any public school without hearing that Santa is bogus. There's always a kid, or several kids, who blow that myth.
If I had a kid that age, I'd introduce him or her to the concept of Santa as a "pretend" character before they went off to school. Better the explanation is made by parents than some snotty-nosed kid.
Bottom line is that belief in Santa ends about then. It must end about then. We send our kids to school at age 6 to begin learning about the real world and what's in it. And learn they will, one way or another.
If parents want a choice about how kids learn about Santa, then they have to act in advance of the kids learning about it in another way, because I guarantee you that in every 1st grade class there are kids who already have that information and who won't be bashful about sharing it with the kids who don't.
I wonder how my 10 year old has made it to 5th grade without hearing that Santa isn't real. I'm so thankful that (at least in my area) it isn't a priority to crush the childrens dreams of Christmas joy.
Having said that I think your advice has merit. Certainly, it is likely true that for many kids, the Santa Claus fantasy is blown by other kids, and it would be well to be prepared for that.
You're missing the point. Kids will continue to tell other kids about Santa, and everyone acknowledges that. However, its an entirely different matter for an adult to butt their noses in where they don't belong to assume a role that isn't theirs to begin with.