Headscratchers / Tricky People

Why doesn't Yello Dyno warn the kids ahead of time to never have anything to do with Reginald Charming? He knows he's a predator, and Charming clearly has enough power to become a dangerous threat to kids. Dyno's basic tips do help for safety, but why on Earth would he not tell the kids one tricky person is close enough and will probably try to lure them away? Is he putting the kids to a test, by withholding information, just in case they meet him, or is he really just that careless?