Kids love snakes, and many mentally hadicapped kids we have seen like snakes more than your average kid.
If your ball python is trust worthy, I would definitely at least let who ever wants to touch it do so. Just stress that they have to pet it nice, and can't squeeze, pat, or beat the snake.
We have let many kids hold ball pythons (and many other snakes). Ball pythons are the best snakes for this, overall, and in general, in my opinion.
If you don't want the kids to come over, take a snake to them.
They are kids, they deserve to get to see reptiles in real life - it might be their favorite experience for years - and you get to provide that for them.
Also, if they get to see a snake at this age, they should never develop fear of snakes in the future.
I say that if the ball python is trust worthy (which 90% of the ones we've had are) definitely let them touch and maybe hold the snake. They might not want to hold it, but I'm sure you can get all of them to touch it - and they will be amazed at how nice they feel (especially BP's)
I've got a bit of a soft spot for kids who are dissabled or disadvantaged due to a handicap, but it is those kids who seem to appreciate someone doing something special for them more.